Well, assuming that it costs $800 to make a set of outfits for a whole band (depending on how elaborate they are) and then another $500~1,000 to do a full photoshoot, it was probably wiser to just do everything all at once to see how the sales went.
I just feel dumb because I'm usually observant. Guess I was too busy staring at the different hair/make-up from the different releases and didn't notice that the outfits were the same. xD