Depends on make, batch and how hard they're hit. I'd say mavis 300's last perhaps... 3 games in good nic, after than they degrade.
plastic last way longer than feather. but off course feather plays better. in pro matches feather last about 2-3 rally points. plastic i would way last about 4 games, even longer depending on the players. saves so much money. haha. the durability difference between the two is significantly big but the difference in playability isn't so much.