Yes, that works, but some games just jump all over the place and signal gets lost. What I mean is that Saturn looks perfect and steady, but you’re bound to get problems at some point with PS1.
What games specifically? I’ve never encountered that. I think what you are seeing are games that switch from 240p to 480i. Using optimised modes won’t help here. Indeed, there are games on the Saturn that do that too unfortunately.
For N64 I just used generic, I remember when OSSC first landed and there was only generic and I was really blown away with how good the N64 looked, and that’s just using a simple amp mod. My console is NTSC though, I can’t comment how PAL games look.