The other thing to remember is try to avoid playing down-tempo around the hour or half-hour mark later in the evening. Depending on the venue, after the time of peak activity (perhaps after say 2pm), some punters may think of leaving the venue and if they look at their watch and it's on the hour or half-hour (i.e. 2:30, 3:00 or 3:30) and if this coincides with a lull in the music, it could be enough of an reason to leave and go home or go elsewhere. Try to keep the tempo and energy high at these times so if they check the time and it's say 2:30 and the music's pumping, there's more chance of them staying on just that little bit longer and perhaps buying another drink or two (which would make your boss happy). If you need to drop the tempo, wait until just after these times. If they look at their watch at say 2:45 and the tempo has dropped, they might say to themselves "I'll stick around until 3:00" and by then the tempo has picked up again. But most good DJ's who can read a crowd should already know this.