Now, I have to do something about it.
It is but keep in mind it is just showing the current battery value which is dependent on accurate battery reporting from the device itself. I mention this because I have 20 or so Centralite/SmartThings branded leak sensors that have terrible battery reporting and will remain at 0% for 6+ months while still working.
I personally don’t pay attention to battery values and use another solution to notify me when a device stops reporting.
As inferred from your post, this is a highly-personal subject. For me, the answer is ‘both.’ I monitor my battery levels, but rely on activity to tell me when it’s time to change them. (Except for locks, which I think everyone would agree with.)
Why do I monitor battery levels when I am using activity to change them? Because it’s there. In some ways, it’s an inconsequential game, but really it’s just learning and recognizing the patterns. I have a temp sensor that has been sitting on 11% battery for months while its identical sibling just a foot away appears to be going through what I would consider to be a normal curve. Bad battery? Bad device? Not sure, but I’ll keep an eye on it, especially after the next battery change. Entering the fall, and my garage tilt sensor is <50%, should I change it now, or wait until it dies on the coldest day of the year?