How is it like for live audience watching long classic chess? For the live audience that's watching chess in person, not online, how is it like? 

Do they sit through it all, say 7h? Can they leave and comeback? Are their seats reserved if they leave? Do they have restaurants and so on to spend their time?

What was it like in the old days, say 90s or 80s when there was a huge crowd, did they sit still for 7h and comeback everyday?  

I just wonder how it like to be in the audience, mainly in FIDE world classic chess championships, lets say the final match, since in theory it should attract the most audience.
I helped out at the 2008 match between Kramnik and Anand in Bonn and attended many other world class events as a spectator. (Like Kramnik-Fritz when he blundered the mate in one. Epic.)

Usually seats aren't reserved and people come and go. Often there is a separate commentary/analysis room that you might attend, although you can also hear commentary with headphones in the playing hall. If you are accompanied by friends you might occasionally slip out to discuss the current position. 

But many people are actually sitting though almost the entire game, with only the occasional toilet break etc. Time flies when you are having fun. And of course 7h games aren't the norm.