That may be true for deposits, but one can apply to as many schools as they want.
Good advice from the last post (by the way, welcome to all new websters to the HSBBW).
Keep in mind signing in the fall is not a guarantee for acceptance, the player still has to go through that process and remain eligible until graduation.
Yes, the coaches usually are pretty good at determining beforehand whether they will be accepted, they usually run the players transcripts by admissions to get a general idea before the player applies. I do beleive in some cases, admissions must approve before an offer can be made.
It is always advisable that any player begin their college search (where they would like to attend regardess of sport, etc) when all students begin, which would be during their junior year, according to GPA and test scores.
Don't worry about a late signing in spring, the coaches take care of that.
For the recruit, one can get a pretty good idea of interest before the application deadline, which is after the early signing period. If no early commitment, decisions will have to be made as to where the player has an academic interest.