Dormant pruning is the best pruning. It happens while the subject plants that benefit from it are dormant and unaware of such procedures. Such procedures would be significantly more distressing to plants while they are vascularly active. In comparison, spring pruning may seem to be cruel and tortuous. Nonetheless, it is justified for particular applications.
For most plants that benefit from dormant pruning, the worst time to prune is immediately after the best time. Such plants are most vascularly active while blooming and refoliating during early spring. They become more resilient to pruning as they finish bloom and their foliage matures. This generally applies to plants that benefit from spring pruning as well.
The primary difference between plants that prefer dormant pruning and plants that prefer spring pruning is their primary purpose. Several plants that benefit from dormant pruning produce fruit. Plants that benefit from spring pruning merely produce profusion of bloom. Dormant pruning concentrates resources.Spring pruning allows maximum spring bloom.
For example, flowering plum is like a sterile but prettier version of fruiting plum. It merely blooms impressively without subsequently fruiting. There is no need for dormant pruning to concentrate resources into fruit, or to compensate for fruit weight. When and if pruning becomes necessary, it can happen after any unwanted growth has contributed to bloom.
Flowering cherry, flowering crabapple and flowering quince may actually prefer dormant pruning like their fruitful relatives do. However, like flowering plum, they also bloom more abundantly prior to spring pruning. Unrelated dogwood, redbud, forsythia and even New Zealand tea tree likewise benefit from spring pruning, which is the same as late pruning.
In moderation, blooming stems of plants that get either dormant or spring pruning can be delightful as cut flowers. A few unpruned stems can remain after dormant pruning for that purpose. They only need proper pruning when harvested or after bloom. Likewise, plants that get later spring pruning after bloom can likely spare a few stems while still blooming. Alternatively, such stems should be conducive to forcing.