M H Swende

So find the best gym first, with the most ambitious routesetters.

Very much is up to the gym, imo. A route isn't just a set of grips. A good routesetter builds interesting problems, that you must work on over several visits and force you to actively _think_ about. Those help drive the urge to come back.
Bad gyms just slap grips on the wall. Smaller -> harder.