Like penguinbc said, it depends on what you're selling. Different products work best with different methods of promotion, and different methods of promotion have wildly different patterns of results - e-mailers often see results in bursts, PPC people are usually pretty steady, SEO people can take a while to see any results at all, etc.
The whole 5 affiliates and 60 sales/day thing is really weird, too. When you take on affiliates, they're taking all the risk in promoting your product, so most of them are going to resent it if you "require" them to do 60 sales daily to be "lucky enough" to be in your elite affiliate promotional force.
Maybe you have some really great reason that I can't think of, but I don't know why you'd cap your affiliates or require certain performance levels. Why not just open it up to as many ethical affiliates as you or your team can manage, then let them do what they can - but encourage them to do more by offering increasing incentives with performance?