Here is a chart from the only study I have seen on taking a gap year. Clearly, the students taking a gap year are not a homogenous group, but it does show that overall, the students who take a gap year graduate a significantly lower rates than students who start right away.
That is the outcome I would expect, simply because the longer it takes, life happens and more and more students have life events happen that prevent them from finishing. While I think the direct to college approach is preferable, there are definitely student for whom a gap year it is the right decision. I just don’t think it is right for most students.
https://nces.ed.gov/das/epubs/showTable2004.asp?tableID=1478&rt=p