Whether it’s PVE, PVP or Season progression rewards, they all stop when you hit 25 cp. It would be nice if there was some bonus for scoring beyond top progression, such as double ISO for each battle, extra ISO, HP, cp or event tokens for additional progression… something to make the extra battles more meaningful.
As it is, you just keep battling away to try to get decent placement, which isn’t guaranteed, so it could be a complete waste of time. And even though you can get some extra ISO from the battles, you often need to spend ISO on boosts, so it ends up being a wash currently.