Typcially lower end components will last longer than that, but will usually require more adjustments.

I would also guess that lower components will tend to break more easily/faster than higher end.

If you are looking at a new bike, I would say stick with shimano 105's which have a great all around performance/durability. I have 300+ miles on my 2200 and have yet to need an adjustment. Although, I think I"m taking it in this weekend for a minor tune.

hope this helps.