I am curious. I have read numerous times that much can be deducted of a hives overall condition by watching the activity around the entrance of a hive. I understand "going through" a hive will set them back to a small degree so if it isn't neccesary I prefer not to.
I can recognise incoming pollen, play flights in early afternoon, robbing behaviour and even had a couple of front row seats to swarms.
I guess my question would be what type of behaviour/observation would send up a red flag to you that would cause you to open up and go through a hive?(besides the obvious like a mound of dead bees out front).
I assume that most larger operations could not possibly check all their hives all the time and would have developed some sort of streamlined way of identifying problems.