Generally, the later the final battle, the more troops there are, and the more difficult the battle becomes. To put it simply, a final battle on day 117 often requires much less time than a final battle on day 147.
If we were to introduce an objective criterion, it would be similar to online poker. That is, the overall timer would be limited, but the decision-making phase for each unit would be limited to, say, 1 or 2 minutes (plus there should be some kind of time bank, the size of which depends, for example, on the game week). And after this time, if a time bank is not requested, the defense is activated. Ideally, the opponent would go into a sit-out...:smile49:
"Совесть - она либо есть, либо её нет" (с) RedWhait HP