However, an hours bouldering... is that enough to keep the improvement curve trending in the right direction??
A long warmup to ensure everything isn't going to explode then an hour of really powerful, steep, basic bouldering on small holds remembering to rest appropriately between attempts. Stopping just as you start to decline.
Like all training methods, training to failure is a tool. No tool should be used all the time for all applications. It can however, be a useful training method. Any training program which plans for progressive resistance, consistency, and variation is likely to produce success
I heard taz had done 90 days on, doing something harder than 8a every day (not sure if that's sport or font)
I wouldn't be surprised though, taz is a beast.
This may be of interest http://www.planetfear.com/articles/Neil_Greshams_Guide_to_Bouldering_for_Strength_205.html