Explanation 
Each placed building piece, companion or container reduces the class bonus by a certain percentage
(it should be visible during the game).
Ideally, it should also warn you when the bonus is depleted. Or at least it showed its value together with information about the change in value (in the message on the right).
I chose for topic that the standard player’s goal would be to keep the benefit at 50% bonus.
As a database I took: the previously calculated minimum 370 building elements; the current limit of companions (65 for a single player); I added together all the slots for the vast majority of furniture (workstations and containers) plus 28x Large Chests.
I also assumed that the most important (the most expensive) are companions and equipment slots should be much less important when placing new containers.
Calculation results 
Basic Example:
When a player places 370 building pieces, 28 workstations, 28 chests, and 65 human companions (T2), he should weaken his class bonus to about 50% strength.
- 370 building pieces x -0.050% = -18.500%
- workstations and containers with 2375 slots x -0.004% Chest = -9.500%
- 65 human followers (T2) x -00.334% = -21.710%
In total, the bonus was reduced by -49,710% so its strength is 50,290%.
Note: In the post above you can see what bonuses are involved.
Further explanation 
Details...
- I took the number 370 building pieces because:
-
I took the number 2375 slots from 56 objects (workstations and containers):
- 28 Large Chest (45 slots each) have a total of 1260 slots (one chest for each workstation present below)
- 28 workstations have 1115 slots in total:
- Altar of Zath (100 slots), Armored Animal Pen (50), Artisan Table (30), Casting Table (40), Compost Heap (30), Dismantling Bench (40), Dryer (20) , Dyer’s Bench (40), Feed Box (35), Fermentation Barrel (20), Fluid Press (20), Garrison Armorer’s Bench (60), Garrison Blacksmith’s Bench (40), Greater Wheel of Pain (100), Grinder (20 ), Heat-Efficient Furnace (30), Improved Stove (45), Large Campfire (30), Precision Alchemist’s Bench (40), Precision Carpenter’s Bench (40), Precision Firebowl Cauldron (40), Precision Tannery (40), Saddler’s Worktable (30), Stables (30), Tanner’s Table (40), Thrall Pot (35), Tinker’s Bench (40), Torturer’s Worktable (30)
Note: I have not counted fish traps because with this solution, it is best to put them only when using them and leave them hidden in the container when not in use. Likewise, I did not count the beehive and objects present only in Siptah.
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I took the number 65 human followers because that is the current limit.
More examples
( practical part of the topic )
370 buildings, 2375 slots, 65 followers T2 / strength of the Bonus 50.290%
- 370 building pieces x -0.050% = -18.500%
- 1115 workstations slots x -0.004% slots = -4.460%
- 28 chests with 1260 slots x -0.004% per slot = -5.040%
- 65 human followers (T2) x -00.334% = -21.710%
Total Bonus reduced by -49.710%
370 buildings, 2375 slots, 65 followers T4 / strength of the Bonus 48.730%.
- 370 building pieces x -0.050% = -18.500%
- 1115 workstations slots x -0.004% per slots = -4.460%
- 78 chests with 3510 slots x -0.004% per slot = -14.040%
- 65 human followers (T4) x -00.358% = -23.270%
Total Bonus reduced by -51.270%
370 buildings, 4625 slots, 65 followers T4 / strength of the Bonus 39.730%
- 370 building pieces x -0.050% = -18.500%
- 1115 workstations slots x -0.004% per slots = -4.460%
- 78 chests with 3510 slots x -0.004% per slot = -14.040%
- 65 human followers (T4) x -00.358% = -23.270%
Total Bonus reduced by -60.270%
500 buildings, 4265 slots, 70 followers T1-4 / strength of the Bonus 37.836%
- 500 building pieces x -0.050% = -25.000%
- 1115 workstations slots x -0.004% per slots = -4.460%
- 70 chests with 3150 slots x -0.004% per slot = -12.600%
- 30 animal followers (T4) x -00.219% = -6.570%
- 30 human followers (T4) x -00.358% = -10.740%
- 2 Sherpa (Bearer) (T4) -00.438% = -00.876%
- 2 Elephants (T1) x -00.263% = -00.526%
- 4 Mounts (T1) x -00.187% = -00.748%
- 2 Entertainer (T1) x -00.322% = -00.644%
Total Bonus reduced by -62.164%
1000 buildings, 5030 slots, 100 followers T1-4 / strength of the Bonus 3.926%
- 1000 building pieces x -0.050% = -50.000%
- 1115 workstations slots x -0.004% per slots = -4.460%
- 87 chests with 3915 slots x -0.004% per slot = -15.660%
- 30 animal followers (T4) x -00.219% = -6.570%
- 30 animal followers (T1) x -00.195% = -5.850%
- 30 human followers (T4) x -00.358% = -10.740%
- 2 Sherpa (Bearer) (T $) -00.438% = -00.876%
- 2 Elephants (T1) x -00.263% = -00.526%
- 4 Mounts (T1) x -00.187% = -00.748%
- 2 Entertainer (T1) x -00.322% = -00.644%
Total Bonus reduced by -96.074%
250 buildings, 1565 slots, 35 followers T1-4 / strength of the Bonus 71.428%
- 250 building pieces x -0.050% = -12.500%
- 1115 workstations slots x -0.004% per slots = -4.460%
- 10 chests with 450 slots x -0.004% per slot = -1.800%
- 5 animal followers (T4) x -00.219% = -1.095%
- 10 animal followers (T1) x -00.195% = -1.950%
- 15 human followers (T4) x -00.358% = -5.370%
- 1 Sherpa (Bearer) (T $) -00.438% = -00.438%
- 1 Elephants (T1) x -00.263% = -00.263%
- 2 Mounts (T1) x -00.187% = -00.374%
- 1 Entertainer (T1) x -00.322% = -00.322%
Total Bonus reduced by -28.572%
Detailed list of values
Warriors, Archers, Entertainers and Sherpa (Bearers)
-- Human Archer I -00.322 %
-00.262 (base human follower)
-00.004 x12 (inventory slots)
-00.012 x1 (tier value)
-- Human Warrior II -00.334 %
-00.262 (base human follower)
-00.004 x 12 (inventory slots)
-00.012 x 2 (tier value)
-- Human Entertainer III -00.346 %
-00.262 (base human follower)
-00.004 x 12 (inventory slots)
-00.012 x 3 (tier value)
-- Human Warrior IV -00.358 %
-00.262 (base human follower)
-00.004 x 12 (inventory slots)
-00.012 x 4 (tier value)
-- Human Sherpa (Bearer) I -00.342 %
-00.262 (base human follower)
-00.004 x17 (inventory slots)
-00.012 x1 (tier value)
-- Human Sherpa (Bearer) II -00.374 %
-00.262 (base human follower)
-00.004 x22 (inventory slots)
-00.012 x2 (tier value)
-- Human Sherpa (Bearer) III -00.406 %
-00.262 (base human follower)
-00.004 x27 (inventory slots)
-00.012 x3 (tier value)
-- Human Sherpa (Bearer) IV -00.438 %
-00.262 (base human follower)
-00.004 x32 (inventory slots)
-00.012 x4 (tier value)
Animals and Mounts
-- Animal I -00.183 %
-00.131 (base animal follower)
-00.004 x10 (inventory slots)
-00.012 x1 (tier value)
-- Animal II -00.195 %
-00.131 (base animal follower)
-00.004 x10 (inventory slots)
-00.012 x2 (tier value)
-- Animal III -00.207 %
-00.131 (base animal follower)
-00.004 x10 (inventory slots)
-00.012 x3 (tier value)
-- Animal IV -00.219 %
-00.131 (base animal follower)
-00.004 x10 (inventory slots)
-00.012 x4 (tier value)
-- Camel / Elephant I -00.263 %
-00.131 (base animal follower)
-00.004 x30 (inventory slots)
-00.012 x1 (tier value)
-- Greater Elephant IV -00.299 %
-00.131 (base animal follower)
-00.004 x30 (inventory slots)
-00.012 x4 (tier value)
-- Horse / Rhinoceros I -00.187 %
-00.131 (base animal follower)
-00.004 x11 (inventory slots)
-00.012 x1 (tier value)
Workshops and other containers (-00.004 per slot)
– Workstations
- Altar of Zath (100 slots) -00.400 %
- Armored Animal Pen (50 slots) -00.200 %
- Artisan Table (30 slots) -00.120 %
- Casting Table (40 slots) -00.160 %
- Compost Heap (30 slots) -00.120 %
- Dismantling Bench (40 slots) -00.160 %
- Dryer (20 slots) -00.080 %
- Dyer’s Bench (40 slots) -00.160 %
- Feed Box (35 slots) -00.140 %
- Fermentation Barrel (20 slots) -00.080 %
- Fluid Press (20 slots) -00.080 %
- Garrison Armorer’s Bench (60 slots) -00.240 %
- Garrison Blacksmith’s Bench (40 slots) -00.160 %
- Greater Wheel of Pain (100 slots) -00.400 %
- Grinder (20 slots) -00.080 %
- Heat-Efficient Furnace (30 slots) -00.120 %
- Improved Stove (45 slots) -00.180 %
- Large Campfire (30 slots) -00.120 %
- Precision Alchemist’s Bench (40 slots) -00.160 %
- Precision Carpenter’s Bench (40 slots) -00.160 %
- Precision Firebowl Cauldron (40 slots) -00.160 %
- Precision Tannery (40 slots) -00.160 %
- Saddler’s Worktable (30 slots) -00.120 %
- Stables (30 slots) -00.120 %
- Tanner’s Table (40 slots) -00.160 %
- Thrall Pot (35 slots) -00.140 %
- Tinker’s Bench (40 slots) -00.160 %
- Torturer’s Worktable (30 slots) -00.120 %
– Not included in basic example
- Convergence Trap (15 slots) -00.060 %
- Delving Bench (200 slots) -00.800 %
- Fish Trap (5 slots) -00.020 %
- Improved Beehive (10 slots) -00.040 %
- Improved Planter (30 slots) -00.120 %
- Improved Fish Trap (10 slots) -00.040 %
- Improved Shellfish Trap (10 slots) -00.040 %
- Shellfish Trap (5 slots) -00.020 %
- Small Animal Pen (6 slots) -00.024 %
– Containers
- Cupboard (45 slots) -00.180 %
- Improved Preservation Box (40 slots) -00.160 %
- Large Chest (45 slots) -00.180 %
- Large Crate (50 slots) -00.200 %
- Vault (300 slots) -01.200 %
Edits / Notes
Note: I will improve the text formatting / add screenshot for the next few days.
Note 2: When I finish formatting, I will write in the next post, how it should work with clans and I will discuss the actual hard cap.
Edit: Screenshot added