I'm aware of the original articles point, my post was of the form "even when you account for X, their analysis is still valid". And neither did I mean to imply

I'm aware of the original articles point, my post was of the form "even when you account for X, their analysis is still valid". And neither did I mean to imply that people actually get maintenance done exactly on schedule. A more relevant question would be how much dead weight loss this bias results in. I'm guessing not that much.