I think 5-10 is great and twice a day is even better, good for you for keeping this up! Great to hear that you've had and continue to have good results. My practice is supposed to be twice a day and maybe one day I'll do that but for now I am doing what is realistic for me instead of ideal because I want to stick with it.
It's a great blessing not to have problems with sleep, I envy that! My sleep problems were from childhood traumas and finally they seem to be gone. The two changes of diet and meditation provided the magic cocktail and I'm SO glad to be sleeping well these days, it makes all the difference. (of course I still lose far too much sleep reading and writing on steemit, but that's by choice :-)