Regular pruning isn't required, if you wish to improve their shape - do so immediately after flowering.

I don't see what part of the country you are in to guess at your soil type...if your azaleas are planted in soil high in organic content (compost, whether clay or sandy base), the main reasons for failure to bloom are -

Too much shade.
Pruning wrong time of year.
Over fertilization produces vegetative growth (leaves) rather than flower buds.
Drought in summer when they are setting buds for the next season's flowers.