My $0.02 worth is that it also depends on the venue. If you are DJ’ing at a “DJ concert” at a large venue – echostage in the DC area comes to mind, and you are opening for a big-name DJ, then definitely follow a tighter set of rules and don’t “peak” the floor before the headliner.
However, if you one of the DJ’s at a more traditional bar/nightclub, then you have more leeway. Most patrons are not there to dance the entire night, they want to socialize with their friends, get drunk, etc. So a “waves” concept might be more appropriate for each DJ. Start out their set with some slower stuff, peak towards the middle/end, then lay down some transition tracks for the next person. Lather, rinse, repeat.