In addition over fishing BG is more likely the colder your climate all other things being equal. Maybe we should be talking about the mortality rate of BG as that is the real question. In many southern BG/LMB ponds the natural BG mortality rate is very high due to LMB predation. This can leave you with fewer but larger BG. That type of pond is easily over fished for large BG.

Like Bill provides it depends on your goals but also on the current status of your pond.