Practice time is a personal thing. I try to get in about three hours each day, close to four if possible. I always space out my playing, ie. play 1 hour, rest for 45 min, etc. Common sense is key as well. Going overboard and doing damage to the chops can put you out of commission for a while, so if I start to feel as if I'm pushing my limits too much, I stop. Also, about "face time," I totally agree that it takes more to improve than just playing. There needs to be some goal setting and some structure. Just my 2 cents.