In my C project I have quite a large utils.c file. It is really full of many utilities of different sorts. I feel a bit naughty just stuffing different miscellaneous functions in there. For example it has some utilities related to low level stuff such as a lowercase() function, and it also has some quite sophisticated utilities such as converting to/from different colour formats.
My question is, is it very naughty to have such a large utils.c with many different types of utilities in it? Should I break it up into many different kinds of utility files? Such as graphics_utils.c and so on What do you think?
If it's just you that will EVER maintain the stuff, it's a matter of when the complexity gets to the point where you find yourself searching for things. That would be the time to refactor and reorganize (there's a cost to reorganize, just as there's a cost to not reorganize).
If it's POSSIBLE that anyone else will maintain a project that includes your utils, you have to consider THEIR pain point when deciding when to reorganize. Theirs is MUCH lower than yours.