I have a Patreon which I use as a tip jar, so it doesn't take much of my time. The extra money is not much, but it all helps. However, if I did offer rewards, it wouldn't be worth it. The big issue is it's for people who are already your fan and willing to commit to regular payments. It doesn't work well for attracting new fans. Rewards could easily end up taking all your time if you're not careful, for very little return.