The CTR of an "average" video is 5% or so I've heard. I think you always want to shoot for a better CTR than last time, so I would change my title and thumbnail periodically to see which results in a higher CTR (this takes a lot of work manually, but the TubeBuddy AB testing feature does this as well).
Personally, I think that if the CTR of one of your most recent videos is 5% and that's the average CTR for your channel, you need to start focusing on making more clickable content. So I say improve it, because all you can do as a content creator is continue to improve, even if you find your content to be successful.