Heroes 5.5 WarGame Edition - Tactical Edition.

Only in the first version did upgrades still scale with fortifications.

Here's an alternative to numerically increasing the upgrade level.
Also, the ability to choose the troop type (base, upgrade, or alt-upgrade) depending on the opponent's strategy.
In the end:
1. additional weekly increase
2. scaling with fortifications
3. the ability to choose the stack type (defensive, offensive, etc.)

In the end, I repeat:

Is any additional upgrade enhancement really necessary?

ps: increasing it from 50% to 100% is just for simpler calculations (since the discussion was about complexity). Plus, it has a minimal impact on the overall army size (not necessarily, 50% is fine).