Two of my three kids (3rd one was a recruit and committed early, so different scenario) made their decisions based on Admitted Students Day, so for us, it was pivotal! For my oldest, she didn’t visit the school she ended up attending until Admitted Students Day- she decided she didn’t love her other options (that she had visited before acceptances), so she threw her hat in the ring to another school last minute and to her surprise, was accepted. At Admitted Students Day she loved the vibe, loved the students she met, the class she sat in on, etc. and it sold her. One and done visit.
Our son visited the schools he applied to prior to his acceptances, however, we went back to Accepted Students Day at two of them, and his least favorite SOLD him - they really rolled out the red carpet, he met specific program heads and got a more in-depth view of his particular college within the larger university and could see what specifically they could do for him. It sold him on the spot.
SO, long story short, for my two, Accepted Students Days were crucial and literally caused them to pivot. It’s a very different vibe than a regular prior visit, and I think the ‘rolling out of the red carpet’ helps wavering students to see all of the possible potential and ‘glory’ of the school, IMHO.