I am sure this has been asked before, but couldn't find it--does flying a route multiple times per day (say 3x daily service ATL-JFK) cause RI to grow faster than if you fly the same route 1x per day?
Nope.
The only real difference is between 7 times a week and less than that.
Thus, on a financial point of view, it's better to let it grow and then to add flights. But competition usually prevents from doing so and everybody jumps on big fat routes as soon as they can.
On LH, though, it can be advised to be more careful, as the breakeven is far and you need to wait months before making profit from such routes.