For us, pubs are either 1 x 45 and 1 hour, or sometimes 30m / 30m/ 45m to finish ( i dont like that personally, but sometimes the rest of them want to do it that way)
And theres a working mens club we do where 3 x 30mins is specified, its typed out and pinned on the back of the club secretary's door. Ususlly something like:
8.15-8.45 - Artist
8.45-9.30 - Bingo & raffle
9.30-10.00 - Artist
10.00-10.40 - 'Play your cards right'
10.40-11.10 - Artist
11.10-11.15 - Encore (yes, even your encore is timetabled)
The first time we played there we went over our first spot by 5 minutes and got told off. Seriously.