Winning a CYGS is not even close to winning 12 titles in a single slam. That is 7 rounds in Bo5 for 12 years! That is, in Rafa's case, turning up for 14 years and losing only 2 matches out of 95. A player could strike lucky in a year when, for instance, his rivals are sidelined and they get a free run and win all the slams. On Federer's best surfaces, he has played Wimbledon 20 times and has only won it 8 times, the USO 20 times and won it only 6 times, the AO 18 times and won it only 5 times. So Federer has 3 cracks of the whip and hasn't been able to win 12 titles in any one slam. That's how difficult it is to totally dominate a tournament.