I would say half and half - some in sun, some in shade. However, I think from the bee point of view, the hive just doesn’t want them all inside when it is hot weather. Their muscle movements create more heat, and the hive is already working hard to ventilate it out. So your colony sends a message to bees to go outside, and after that, it is up to them where they hang out. Once it cools down, Nasanov pheromones direct them back into the hive.
I have to say that since I started using slatted racks (salted rats for @skeggley ), I haven’t had any bearding. But then we only had about 10 days above 32C last summer.