Quick question on Crafting~

You can earn chests from achieving S rank on a champion after a game, but if all your chests are down and you receive an S on a new champion, is that champion no longer available to earn a chest from since it was your first S on that champion or will you earn a chest still next time you get an S and have a chest available to earn actually?

Cause all my chests are down and I'm almost afraid to play PvP in that I'll get an S on a new champion and lose a chance to get a chest on that champion then later on down the road. Do I have to worry about being awesome or can I go ham, get those S' and still get a chest later on once one is finally up?