I would say if your buying novelty buy small amounts 1/2 yard can go pretty far.. if your thinking of building stash I would say buy blenders, tone on tones.. those don't really go out of style even the wild colors which can be later used for sashing or a thin border around a block to make it pop. I have probably 40 1 yrd cuts of fabric with 'no purpose' florals or a patterned fabric say Hawaiian prints
but eventually a good portion get used. Don't buy a lot of anything without a purpose. and if your feeling like you just want some.. fabric.. buy f4's. You can always use those in a scrap or sampler quilt, you can use them in wall hangings, table runners etc.. I do agree fabric goes out of style. This last Christmas I saw a lot of aqua and red and that funky green in fabric for the holiday. I know that will be gone in a year maybe two max.. so loading up on that would have been a bad plan unless I wanted to wait til it comes back in fashion say in 20 yrs. Some traditional prints stand the test of time.