I constantly educate customers that we'll 'see you in 4 weeks weather perimitting'.
Often I get fed up of saying the same old thing that we aim for 4 weeks but if it rains then it all gets behind but I phone them before hand anyway so I've never had a problem.
As for the maximum number of customers..... how I'd love to be at position.
We tend to stay at about 80% full because every time we get to that point I put the prices up on the cheapest jobs or the ones that are the most arkward or the customers who are a pain. Anyway, sometimes it's nice to have an easy day.
As a result, bit by bit, we are making more and more money.
Cheers