Hi Grannie.
SFQ isn't something that you have to spend a certain amount of time, or a lot of time, doing. If you get SFQ level 1, one thing you will encounter regularly is Master Lin saying that there is no right or wrong way to do qigong, just good, better, best. If you practice 10 minutes a day, that is good. If you practice 30 minutes 3 times a week, that is better... He also says that the more you practice, the better, and that practicing every day is better, and that 2 hour sessions are best, but he then makes it clear that if you can't do 2 hour sessions, then 30 minutes a day is still good. Another thing I read is that he recommends practicing a lot the first 2 months to get a good start, then backing down the amount you practice.
Personally, I have level 1, and I am a full time mom with a husband and 2 little boys, one still preschool age, so I don't get much time to practice. 30 minutes about 5 times a week is the most I can hope for. I am not experiencing in miracle cures or anything, but practicing qigong feels good, some days really good, and my days seem to go better when I practice in the morning.