I was 100% in during much of that time, so they weren't all that bad. Yes, the bus trips could be rough and the afternoons could be something of a grind, knowing you had to slowly work your way through the crowds and sit on the bus for another long ride and then get ready for the next day. Four or five days of that, and you were glad when it was over.
But there was a lot to enjoy, as well. In 1979, we moved from the South Bronx to an apartment further east (still in the Bronx) and started going to a different congregation that was in a different circuit but the same district. So the big conventions were a time to connect with people we knew but rarely saw anymore. The dramas were fun to watch. The announcements of new books/tracts were exciting. And you would occasionally get a speaker who was very good at keeping you listening (sadly, those were always too rare).
It was just too long. Including travel, we were looking at 10-12 hour days sometimes. And four or five days of that was draining. Not as bad when I was in school, since we would just go right back to summer vacation. But once I was working, it got tougher to get through the week of work, the convention weekend, then another week of work.