Yep... noticing that one day in a list I had a the time was when I decided well if that's how it's going to be maybe just skip reading specific threads for awhile.
My own experience has been that in threads in which one is a participant, or those one is at least temporarily quite interested in following, it can get much harder to follow the thread after awhile: you don't see ignored members' contributions but the flow of the thread to relevant subtopics and back to main topic can start to seem incoherent, when in fact it may not be all that drifty.