[unluky]

Depends on your version of "OK". Most will say do it all and use premium parts. I have replaced just pads many times in my life on many different cars. Likewise I have replaced rotors without pads to, but I do always do them in sets (per axel, not always all 4).

Kind of a personal opinion kind of deal, you will get the full spectrum here. I also do all my own, so as stated above - that pays for a LOT of parts to just do it while you are in there. If $ is an issue - replacing pads only is usually fine - just inspect everything while you are in there and if in doubt - replace.