I have done this before once, though I do find that each 'spool' of color is a bit too small especially a bowden setup as there's a good amount of waste there.
Which does work for some projects, but then not terribly viable for medium sized projects especially if I need just a bit more. I need a Goldilocks solution! lol
I might have to look more into buying more multi-bags though, nice idea!
There are some things I do paint as a result of my struggles lol
But sometimes I don't want that aesthetic or that painting so many tiny things doesn't sound appealing from a labor perspective, etc. But yes, it's always a valid option!