Pruning Azaleas the correct time of the year is critical to their bloom cycle in the spring. I have watched people over the years prune the azaleas whenever they look bad. That is definitely not the best way to improve the look of the shrub in the spring!
According to the textbooks, prune your azaleas right after they bloom. After that, do not touch them. What they will do is rejuvenate themselves and bud out in the fall with the new blooms for next year. Follow this and you will always have beautiful blooms for all to enjoy.
Happy Pruning