It’s a good question. First of all while there are some outlier teams, I really don’t see very many teams where I’m at (P3) that have a base that the other teams cannot beat. Even the very big bases down here are usually quite terrible (I guess that’s one reason they’re in platinum). So the potential for 250 is almost always there. Like orca said:
And they have limitless attempts. So as long as the potential for 250 is there (there isn’t one base that is unbeatable, or one team isn’t down players) teams here have the expectation to get 250.
That expectation can cause a lot of ridiculousness in plat league. We kick players immediately for missing wars. Those players are immediately replaced with alts because if you’re 49/50 the entire league will declare war against you. Now teams would rather play with 15 alts on the team than 50 real players, because the semi-casual players no longer really fit into platinum league, however it is extremely difficult to recruit players who are serious enough. This also contributes to 250 flames becoming more the norm. It is very common for platinum teams to have many alts, and alts always do their war attacks.