That's exactly what I used to do. I'd buy/bid on no name motors listed on eBay for testing... narrowed down my Kv sweet spots for my rides over the years. Speed calculators, and recording temps helped a bunch. I went from 5700-ish > 4600-ish > 3800-ish > to my now current 3000~3500kv sweet spot...
I couldn't decide for another person. Me, I'd be more than content with a 3250kv motor in a 1/10 scale SCT 2wd platform... on 3S it would be bonkers to me... would need a lot of open space to open 'er up.