Yep I work shifts and that tends to be the case in most things, quite often on a Tuesday I leave for work at 3pm so maintenance screws me most of the time. This Tuesday I happen to be off so lose a good few hours there. People say, "Just do something else that day" but for people like me who works shifts like 3pm - 11pm, 5pm - 2am, 12pm - 10pm, 8am -5pm randomly every week and whose days off are different every week it doesn't work like that. With my shifts this week my day off on Tuesday would have been a good chance to play a bit before my girlfriend gets home from teaching which I'll be missing with the maintenance.
That being said, maintenance is what it is and my job is what it is, I'm always going to get screwed working the rubbish hours I work when most of my friends work 9-5. I'm doing the Bupa Manchester 10k charity run in May so I'll be getting out for a run Tuesday while they do maintenance.