Directly from Apple? Never. Third-party sellers like Target, Walmart, and Best Buy (IIRC) will frequently discount the remaining colors of a "season", around the end of that season, but that's hit-or-miss. Beyond that, /r/AppleBandMarket or eBay will frequently turn up "new in box" (occasionally unopened) bands. (On eBay you have to be wary of sellers who use Apple's original photos to advertise, then actually ship cheap silicone knockoff bands.)
If you see a band that you really want, buy it. Do not wait for it to go on sale unless you want the possible heartbreak of never getting it at retail prices. There is a long list of folks, including me, who wish they had the Ultra Violet band. I have a few others I wish I'd have purchased but wasn't fast enough. Hyper Grape and Dragonfruit are two recent and popular examples which sold out faster than some of the others. End of season sales do happen. Some of them can be quite good but you're rolling the dice with which ones will be left and on sale.
As an aside, Best Buy had a whopping $4 savings on some Apple Sport Loops on Cyber Monday.
But the answer to your question, is yes, they do. I bought 2 of them for 50% not too long ago from Walmart.com. I've seen it happen at Target and Best Buy as well.Threads will typically pop up here when they are. Here's the thread that popped up here when I got mine!