When should I prune “non-flowering” deciduous shrubs?

FAQ
Question: 

When should I prune “non-flowering” deciduous shrubs?

Answer: 

All shrubs flower.  However, the flowers of some deciduous shrubs, such as winged euonymus (burning bush), alpine currant, and fragrant sumac, are small and inconspicuous.  These shrubs possess attractive foliage, fruit, bark, or some other ornamental feature.  Prune shrubs with inconspicuous flowers in late winter or early spring before growth begins.