I'm interested in the answer to this too, J_corva. It's been my understanding that the main advantage of scouting trips is that they can't be rejected by a prospect - thus making them useful in pulling down players who wouldn't otherwise talk to you.
I promised some minutes in my first-ever recruiting class, but it backfired on me when the player didn't get as much as he was expecting. That severely limited my ability to shuffle the lineups around as I looked for a winning combination. And, of course, the player's WE fell a bit until I managed to reshuffle enough to meet my promise.
This recruiting season now ongoing in Smith, a couple of people have told me the same thing - save the starting promises until you're low on money and in a tight race for a player. It's a cheap way to sew them up if you're almost broke.