It wasn't when I was flying it; it would generally break hard at least once a tour, and if it didn't, I had to make a fatigue call for my safety. There's no way in the world you'll fly 600 hours a year in it, I can guarantee that.

400 hours a year is possible, but much more than that is hard to come by unless you pick up and drop off your plane without an airline flight (very rare), never get sick, never fatigue, never write a plane up, never get Reserve, Hot Spare or Tentative duty (completely out of your control), gets lots of flight time scheduled (also completely out of your control), don't have customers with 2-hour departure time windows (fairly common, and out of your control), never have another crew take your plane because theirs broke (and you have to airline to another one), and so on.

There are just too many other factors that make such high flight times unlikely on a regular basis. A significant portion of the job is the stuff done between flights, and that isn't going to pay any bonuses.