As a classic introvert I don't really care how long conference sessions are, because I won't be there.  Too many people in too small a space just makes me very tired and in need of a bit of solitude.  Although the sessions may be interesting I never learn anything because I am too anxious about getting out quickly at the end and avoiding being caught in a crowd.  As most conferences have videos of their sessions available afterwards these days I can catch up on those subjects that I want to know more about in my own time, at my own pace, and (more importantly) on my own.