If there are no decent rounds that can be produced, why force a new round? Personally, I really like Codeforces' system. Plus, I like time variation: on AtCoder I can't participate in any round, since it's 5am my time (pst).

Every competitive programming platform apparently prefers weekends for their contests. Some of them would need to move contests to weekdays in order to avoid contention. But who is going to voluntarily do this?

The end result is that I have to pick just one of the clashing contests and skip the others. If they were more evenly distributed, then I could participate in them all. In the past I tried to participate in multiple contests on the same day, but my performance drops significantly and I stopped doing this.

Problem setters determine it, I think.