I practised these exercises for at least an hour a day, though I would normally try and practice for two hours, if I had the time. I would always make sure to have a five min break every 20 mins or so to give my body and mind a rest and then go back to it afresh.
So there you have it! I hope you find this useful to your needs, and I wish you many happy hours of drawing and designing. You deserve the best of it and this should give you a good foundation to work from.
I’ll see your art in the galleries, websites and magazines of the world.
Mark. A.K.A Dusty @[^.^]@