/vr/ - Retro Games

To anyone familiar to Mega Man or just NES sprite editing, I have two questions.

1) Obviously the sprites are divided into several tile banks, which go from 00 to 3F. For instance for the MC, the idle, running and shooting frames use tile bank 0, but the jumping and ladder frames use tile bank 1.
My character hack requiring more tiles, I've already started moving some frames to other banks to save space.
The question is: is there any limit to this? any reason why I should stick to as little tile bank change as possible? As far as I understand, for every new frame the game loads the corresponding tile bank, and reloads it if it's the same as the previous one anyway, is that correct?

2) Tile flicker. Sometimes, a few tiles will flicker even in the original game.
Is there any way to control it? The game seems to be designed so that the 'least important' frames tends to be the one which will flicker for MM, but maybe it's a coincidence?
And what causes tile flicker to begin with? I understand there is a tile count limit but this seems to have nothing to do with it. In MM5, in some situation where you're just facing ONE Metool there will be some slight flicker, and in the same situation a few steps later there'll be no flicker. What the hell?

Pic related, on the left: tile flicker for a couple tiles, on the right: no flicker. This happens in the original game too.

Thanks