well it also depends how hard of plyos he's doing. i mean, basketball is highly plyometric, but you can play every day if you're not going too hard.

but the more important issue with doing plyos so frequently is that defeats the point. they're not an endurance tool. do too much volume, then your body will adapt to the hiigh volume and you'll never gain. best way to do it: as soon as you hit a PR stop the workout. really thats a good way to handle any workout, plyos, weights, sprints, etc. once you hit a PR stop