In some fields, it is hard to get that first full time job without relevant summer work (job or internships). So cutting out the summer between junior and senior year is not a trivial decision. Your kid may walk in with advanced standing, but the resume may look weak compared to someone who is an actual junior (i.e. in their third year of college) compared with a kid who is a technical junior but really a sophomore counting from the beginning.
So think through the consequences of accelerating. Fewer professors to write recommendations. Less time to work editing a professors book or helping a Dean with a presentation for a major conference. Less time to spend volunteering in the college community in organizations which are the “fast track” groups for meeting politicians, corporate leaders, etc.
One of my kids got a fellowship for the summer after graduating (had already accepted a corporate job with the company where the summer job had been the previous year) just on the basis of a professor saying “You are starting a full time job in August? Why not do some travel, some writing, some research before you do? I can help you with a fellowship?” and a month later- boom. On a plane, got an extension from the company to start a few weeks late.
It takes some kids time to cultivate these kinds of relationships.