I think it was something on the order of 30-40% of our fleet is in a mx base nightly. Pulling into DTW one evening just as the jetway pulled up a mechanic walked up and said our aft nav light was out.. can't complain!

As far as TYS that happens every morning - we do the first flights to ATL (x2), LGA, DTW, MSP and I believe JFK. Thats just the nature of being a maintenance base - same happens in DSM and IND. TYS seems to have a lot of -900 service and if it isn't that it's a 717/MD90 on the route so I doubt it would be our "southern" -200 base.