I could never get horny in the mornings, I have no idea how some people can. I have never waken up to morning wood, from what I can remember.
I usually try to take it slow and make the masturbation last a while - at least 30 minutes but closer to an hour (not counting the time beforehand that I like to give myself some "foreplay" by watching porn or reading erotic fiction). But if I'm really horned up, I'll probably go mad if I tease or edge myself, so I just want a release and then will be all horny again an hour or so later - this happens all the time, and sometimes went on to three or four times. I think the most I've ever done was five within a six-hour time frame, but that was only once, and my balls hurt like heck afterward.
So, usually once or twice per day.