If I was England manager, I would only give caps to people who I felt pretty sure were going to be in my final squad for the next tournament. Some people seem to think friendlies are a bit pointless, and / or that they're a chance to give fringe players a go in the shirt to see how they do. I totally disagree.
Most PL teams play 40-50 games in a season, and train together for about ten months a year. International teams get nowhere near that. I would see every day of training and every friendly as a rare and vital opportunity to get my best players together - to get them used to playing with each other, to get them used to the system that I wanted to play, to get them to feel bond between them - essentially, to make them play and feel like a team.
What is the point of playing players in friendlies who you doubt will be in your squad for the next tournament? IMO it's a waste of a rare and precious opportunity.
Capello capped 63 players during his 4 year tenure (
http://www.englandfootballonline.com/teammgr/Mgr_CapelloPlyrsApps.html). I appreciate that over four years players' form will change, and some youngsters will come through whilst some older players will fall out of the picture. But that seems pretty wasteful and pointless to me, when generally about 15 players get any significant playing time in a torunament.