The one guy I knew who'd consistently turn a quick async 5- or 8- message Slack between two or three people into a 15-minute scheduled phone call also double-booked a whole lot of his time and didn't seem to do much aside from say one or two not-very-useful things in meetings before leaving in the middle of it for the next one.

I think he just wanted shit to stick on his calendar for the sake of having a (more than) full calendar, which I'm guessing he found useful for advancement or deflecting criticism. Given some of the other stuff he did and said I think an awful lot of his behavior was one kind of career-hack or another.