i like this site for questions like this, really opens things up i never thought about!
Erm i think when you know the parts to each section and can play them fluently, its then up to you and your band which order and how long you play them for!
i use drums to keep time but then follow whoever is playing the main riff melody be it vocals, guitar ect
Ive seen some bands open sections up a bit longer such to say there thank yous, welcome we are _______ or to put some kind of solo in RHCP do this ALOT and i cant complain

iv also seen sections cut out by some bands!
I used to jam with some friends were wed do the above just to have a mess about!