There is no "normal" when it comes to enjoying a wank. Every guys sex drive is different and it changes constantly too depending on so many factors.
For instance, I know I'm more horny in the middle of summer than any other time of year.
The only time you know you're wanking too much is if it becomes uncomfortable, or it's affecting your life in some way.
If you find yourself canceling social outings in favor of watching porn and stroking your cock, or you're late for work, or you miss a meal because you're too busy jerking your dick, then you have a problem IMO.
Until then, you could be wanking twenty times a day and it's not a problem.