In reply to JackM92:
Absolutely not a waste if done well, however many people's training is not actually training but just playing on routes.
Examples of training benefits...
Falling- if you are unhappy falling on closely bolted indoor routes, how could you possibly be OK falling on spaced bolts or gear?
Technique training - technique totally changes once you start redpointing indoors, just paying attention to breathing, accurate footwork when pumped, optimal clipping stance, the ability to fight to the end on a route. All these things can be trained indoors and will not generally magically appear when you decide you want your first E2 or 6c or whatever the grade.
This is only mental so far, there are a million physical things to actually make you a better climber physically as well.
E.g. stamina - your ability to recover both on and off the route, simply spending 15 min continuously on the wall will improve massivelly your ability to hang around on holds fiddling gear and recovering afterwarda or shaking out on those jugs before you committ for a crux on a sport route.
Of course there is finger strength which would be a revelation once past about f7a and how simple training can have massive effects...
Then again I might also be biased as I really enjoy the coffee and cake indoors.
Post edited at 11:05