it depends..if its a new song that the band is jammin, u will need time to get the dynamics and tightness right..so it may take a few takes to get it right. so nothing wrong jamming a few songs in an hour.
well, i don't know about other audio mixing engineers here. but when I mix a band's song I listen to it at least 50 to 100 times on repeat 1 until I know the song structure more than the band most of the time (ironically).
and it's bands that's practised/played that song over and over again who will learn to tighten up. would you jam 1 song per 1 hr for 3 days (1 hr per day) to tighten up , until your band mates know the song by heart, play until wanna vomit already. or 3 songs per 1 hr for 9 days (1 hr per day) and still have your band members forgetting the parts and all?
my bands usually do 1 song per hour which you might think its sian but its good to utilise the time to improvise and sort of improve the song and have it done your way.
Think dream theater......beating round and round the bush, with extended improvisations and solos for everyone.....suddenly....WTF one hour gone alr ah!? s.h.i.t