Before I make a comment, I try to read most of it. But, for really long threads, I figure someone else has already said what I would have said. However, Barnbum's (sp?) thread about her rescued puppy Buddy went well over 100 pages and I read every one of them. So, guess it depends on the subject.

It depends on how much time I have that day and on whether the posts would contain interesting thoughts or guidance, etc. I skim over chains of "Beautiful!, Gorgeous!"
Once a Topic gets past 4 or 5 pages it gets to be too much to read them all, but I still will post if the topic is interesting. Especially if it involves something creative.
I also like to ressurect older topics, especially of beautiful projects people made that didn't get enough air time by posting on them.
:-)