My first set is usually pretty long ... at least an hour to an hour and a half ... then a fairly short break ... I've also gone straight through if the crowd is good ... heck, I do that at home, why not when I'm getting paid?!? ... I feel I get paid for 'setting up' and 'breaking down' ... I would rather be playing than standing around ...
but I know guys who work regularly and it's like 45 min on 15 to 20 min off ... that's not for me ...