It could be 10 scouting trips, it could be 5, it could be 20 or 30. Lots of coaches do it in blocks of 5 or 10. The reason for using scouting trips instead of any other kind of visit, by the way, is that the recruit can't refuse them. You just show up at his games. You get recruiting credit for that. He can't refuse materials through the mail either, but there's just not enough "effort" there to make it worthwhile.
supersloth33 is right, also, that unless you get a backup message, you have *no* shot and should not put any more effort into the player. Just remove him from your list.