Just my two cents… keep in mind that campus visits are part of what college track for demonstrated interest. Some schools track this very closely, and I’d guess that the smaller the school, the more important it is. As a result, you should try very hard to do campus visits through the scheduled options at the admissions office. If you do your own self tour, make sure your child interacts with the admissions office before and after the tour (you may need to help them with what the emails say). “Contacts with the school” is also a frequent question Common App, where you list out the ways you learned about the school.
To check these issues out, you should look at the “common data set” for the school (if it notes that interest of applicant" is at least “considered” then you will want to make sure you’re in the game on this detail - and there are a few schools that consider it “very important”) and also create a dummy account on Common App to see what the school questions are regarding contacts.
With the time and effort associated with this process, make sure you’re tracking these issues carefully (and well ahead).
Also, you should research interviews in connection with the campus visits (and in general). Many schools allow you to do an interview during the visit, and for a (very) few its the only option for interviewing (Denison cut off virtual interview options part way through early fall this year… so our child had to visit campus to get one, and it was a bit of a scramble). You’ll have to gauge your child on whether they’re ready for interviews during your visit. Even though we visited schools all through junior year, we postponed all interviews until after junior year so our kid could mature a little and develop more engagement. We did all of them from start of August through early December - but note that some schools (e.g. William and Mary) end interview opportunities by the end of summer, so do your homework carefully!