My best laid plans are usually to cop when I glance down at my watch and realise that my first set has been an hour and 45 minutes long!! LOL!!!! Playing 9:30 to 1:30 most gigs, that surely cuts down on the rest of the night... I'll take a half hour or 45 min break after that and then get back up and finish off the night or do two short sets with short breaks... depends on the mood of the pub...
Play it by ear is the best bet... if ya have the crowd keep playing... Ya only live once eh!!
{~`