People do seem to be spacing much better on the beach this year, presumably due to Covid. But Saturday was the first really hot day, once it gets hotter they will cram closer to the water. I do wish there was a way to enforce a policy of arrival time corresponding to allowed locations to setup shop. It would be almost impossible to enforce unfortunately.
I also went to Squan on Thursday and it seemed very crowded for a weekday before school dismissals. I was theorizing that perhaps a fair amount of renters are down more often/earlier due to being laid off or work from home.
It's been a real issue on Main Beach. They stopped people from entering last weekend due to overcrowding and yes it's been apparent that folks are staying whereas they would head out on Sunday in year's past. Like you said they have no reason to leave.