I usually don't stop watching until I've been bored with the show for quite a while.

That's me as well. With ER, it's like FOURTEEN YEARS. I was in middle school when that show came on the air. We watch it now just because we've invested SO MUCH TIME. It's actually on an upswing right now but we tend to joke about how all of the plots are so recycled.

so changes like that don't affect me much, unless I see them as a symptom of a bigger problem

Interesting!