My characters hardly ever change clothes. Partly this is because Masahiro is a ragged hobo and doesn't have any other clothes, partly this is because quite a few of them are wearing a kind of uniform, and partly this is because those characters who aren't a.) ragged hobos or b.) in uniform tend to be in the story only for a shorter span of time, so changing clothes isn't really necessary.
I do have characters coming up later in the story who will change clothes occasionally, but it'll mostly be for stuff like changing from casual clothes into armour, or from current outfit to a flashback with a past outfit.
As for defined colour palette - yes, they do have that. There are those who have the uniform, as mentioned, and different groups have different palettes. Like, the guards and staff of a particular castle have a particular palette, the villagers of a particular village have similar palettes, etc., etc. I pick palettes based on mood and story-relevance. Masahiro's got a lot of neutral greys and beiges - partly because it fits his personality, and partly because he needs to work in a lot of different lighting conditions and settings. I've got a character I'll be introducing later who will be wearing a lot of washed-out blue shades, etc.
ETA: Just for fun, I once did a "draw your characters in a different/modern setting"-challenge her on Tapastic, and kept the colour scheme the same!
