Unless most of them participate in weekend activities. This is such a nuanced topic as there are students who choose the day option in order to pursue an elite sport or otherwise engage in activities outside school and disappearon weekends. There are also local day students who choose to attend BS because so much happens at school on the weekends rather that at the houses of students whose parents are away.
Part of a prospective boarders exploration is around how day students participate in weekend activities. I can think of one school, not on the OP’s list, that has a high boarding % that clears out on weekends. A boarder who found it miserable transferred to a different school, again as a boarder, with a more equal day/boarding mix and had much better weekend experience.