My old neighbor used to prune his every August, right before he left for the midwest for a month every year. When he got back in September the roses would be just ready to bloom again. I would do a moderate pruning in August if it were not just too darn hot in August. The canes can get sunburnt then without foliage to shade them.

It's way easier in the cool weather of mid-late January, and taking off the slightly rusty foliage at that time keeps the rust down the rest of the year.

Twice a year, moderately each time, seems to work well. I just can't face gardening in the heat of August.

Some roses like a very hard pruning--the Portland class (Rose de Rescht, Comte de Chambord) responds to a hard wacking with a huge burst of bloom and new basals, while the Teas (not Hybrid Teas) prefer little to none--just dead wood only.