The river policed rules (to coin a phrase) are good ones for making general sense and generally follow a geologically sound pattern based on generalities found in nature, at least on our earth. (and i'll say it again- generally! hah) Regards the river police and inland salt basin seas etc, I've seen those posed as examples many times as exceptions If you want to, you can find examples that contradict nearly all of the specific citings that have been handed out (except perhaps water flowing uphill). Of course there are exceptions, but as you point out, that's exactly what they should be - exceptions, not rules.
if your world has it's own rules, i think the call at that point is to ensure that those rules are followed consistently throughout that world. Consistent internal logic is important to the believability, which in my case at least, adds to the enjoyment.