Well, you could go with the more simpler route and just use one short but high-quality vocal sample, or you could go absolutely nuts with several samples but losing most of the quality in the process, with Super Drift Out's OST being the prime example of that
Killer Instinct's TJ Combo theme is also a pretty great example of voice sampling, and there's even this game right here which honestly has really great quality in it's voice samples, tho it's music is not really that memorable IMO (tho I haven't checked the entire OST since I literally just found this while searching for random SPCs on Zophar a few days ago, mostly to see if Square did anything on the SNES that wasn't a RPG; a silly reason, I know )
Honestly, I think the best way to find great songs with great voice sampling is to simply go a bit obscure, because not many truly popular games have really experimented with voice sampling on the actual music instead of just SFX; a few ones did tho, like DKC, but still
Changing the sample at 30Hz or "30fps" wouldn't sound anything like a real streamed sample anyway. 30Hz is way too little to make timbre changes sound natural, I'd like for you to prove me wrong though. I'm really skeptical that it will sound even remotely human.