When I first started out, I sometimes spent 5-7 hrs a day practicing, but at least 30 hrs a week. I did that for about 5 years on and of in my teens and early twenties. And at the time it seemed pointless, as I did not end up a professional musician. But man I thanked myself for that, when I later returned to music from a different angle, and became more serious. Those early years of practicing are very formative of the musician you will become, and I can almost ascribe all my technical ability on guitar back to those days of practicing. I later polished my chops ect., but it was those long days of learning good habits and theory that made me a musician.

Today I still practice, just in a different way. I practice parts I improvise forth, which could not be done if I didn't mastered my instrument of choice. When I've come up with something, I now can usually play it well in a short time (an hour), but there sometimes are parts I practice for longer untill they sit well enough to sound good on a recording.

I'd say, no practice, no musician.