indeed, I was using fixed point maths on PlayStation 1 games in the mid to late 90s. It was often responsible for the gaps you'd see between polygons on many PS1 games.
Gaps were mostly a sign of sloppy developers and rushed schedules. Compare Tomb Raider 1 on both PC/PSX with Destruction Derby (reflections) and Gran Turismo 1/2 (polyphony).
Yes, there were ways to avoid it (shared vertex calculations), but the effect seen was mostly where there are two separate vertices that are supposed to be at the same position, aren't, because each vertex was positioned with different transformation matrices.
I remember doing a Gameboy Color game after working on a PS1 title. And even though I came from an 8 bit 6502 background (BBC Micro), going back to it was hell. 'Bracing' is an understatement! I couldn't imagine much worse these days.