I have a Roku 3 and I have noticed the batteries degrade faster than I feel they should. Might be a bug that is draining the battery over time for some reason.
I just got some rechargeables and swap them as needed, really not a big deal for us. Rechargeable batteries have come down in price a lot with Amazon Basics starting to sell them.
I did exactly this, after changing the batteries multiple times in a month just got a set of rechargeable batteries for it. Still an annoyance though after sitting back and the remote does not work.