Capping bookings to prevent overutilisation

We've started using bookings to provide forecast information and to help visualise the availability of our consultants. We also use schedule requests so that staff can pre-book periods of absence (for Training courses etc) in their timesheets.

Unfortunately, this tends to create periods of overutilisation (double bookings). Usually this happens when we've put a booking in covering a period of months for a consultant on assignment, and then they schedule a request for training in the middle of that period - hey presto! Double booking.

Does anyone have a suggestion how we can automatically "smooth" the bookings, by for example, capping the time bookable to 8 hours on any day? If not, we have to manually go in and create separate bookings that surround the schedule request - a real pain!