I've achieved "acceptable" results in animation with 1 frame duplicated three times to fill a 30 FPS timeline (was working entirely in video, no film step, sadly.) By 'acceptable' I'm using an entirely subjective measure that says I didn't feel like I was watching cheap animation, just that my animation isn't very good.
Back to the original subject, the only negative strips i have laying around right now are some Fuji Reala 500 that I absolutely murdered (intentionally) by over exposing 3 stops, then pulling 2. While it's interesting, it's too hammered to give any objective statement on. That said, I have some Plus-X that I'll be shooting soon. Once I'm done my camera tests those negative strips are pretty much useless, so I'm not too worried about exposing them to dust in order to clip a strip and run it through my enlarger for the sake of internet science.