Yes, 4:30 is plenty. I am a remote salary employee at a consultancy firm and work less than that.

I've worked at three other web firms and always had to pad my "billable hours." A boss gives me a project with "x" amount of hours and I'm not going to say "well, I can do this in half the time," because they'll just give me more work with no additional pay.

If I were truly motivated I would start my own firm. But I don't like dealing with clients or writing functional specs; I only like to code.