I normally use mine for special dining when I'm out of town somewhere that the spending is more than normal. But this year with the lack of travel, I used mine to pay off balances on my cards.
Been saving it lately, but normally, I use it for statement credit because almost all my spend goes to points for travel.
I traditionally have focused on travel cards, racking up miles or points to be used for flights and free hotels, this has worked out well for me since I love to travel, and while I still plan to travel, probably even some road trips in 2021, my wife and I are ready to start trying to have kids so the frequent flying will likely come to a halt, this means that I will benefit more from cashback in the future. The biggest cashback bonus I ever had was on my Costco card ($456 back after the first year). $300 was used at the Costco and I pocketed the other $156 as spending cash.
I think for Discover cash back now that I am using that card more, I will transfer to savings or contribute to my Robinhood account (I like gambling on he penny stocks). Traditionally I always used UR's for travel, that may change and if I do it will be more money in savings, same with MR's (I don't get a ton of them with the Everyday).
