Even though you see classmates do it, you really shouldn’t play on the same reed, every practice, every day. That single reed will wear out more quickly because it’s taking the brunt of the work. As it breaks down and gets weaker, your muscles don’t have to work as hard, so they get weaker, too. Then, when you do put on a new reed, it feels extra-hard. Plus, what happens if that one reed that you use breaks... right before a concert? You don’t want to play concerts, recitals, auditions, or playing tests on a new reed - they’re too unpredictable. Instead, have three or four reeds going at once and cycle through them: one today, a different one tomorrow, etc. They’ll last longer, you’ll stay stronger, and you’ll always have a couple of backups just in case.
*Bonus - by rotating your reeds, you'll have to take the reed off the mouthpiece and put it away. Think about it, when you're done playing, the inside of your mouthpiece is rather warm and wet. Then, you put on the mouthpiece cap and tuck it away into a cozy case. Wet + warm + dark = ? You got it... MOLD! (ew) It really can make you sick, so when you're done playing, take the reed off, lightly dry it between your fingers, and put it away properly.