It sounds as if the previous beekeepers were a little careless. The very sound advice I have had , and I intend to keep it, is that you should not do full hive inspections when there are others on the site, so weekends could be tricky. Fortunately, retirement means I can be there at any time. Bees can be unpredictable especially during the swarming season (April-August approx) so it pays to have gentle bees in the first place and then to take care when you are looking through the hives.