I've owned and steadily enjoyed a McIntosh MC275 tube amp and C2600 tube preamp since late 2017. I've never tried to estimate the cumulative hrs. of listening, but it's up there. I purchased a complete replacement set of replacement tubes for both components from McIntosh a couple of years ago, and stored them away for eventual replacement. I don't recall seeing any bias adjustments and frankly didn't know it was a thing. I suppose it's time to swap them out!
@rickisme , I just did a cursory search & I am picking up that the newer 275s are self biasing. Other wise, occasional checking & adjusting the bias of output tubes is a MUST. Especially after installing a new set. Your owners manual should clarify that for you.