Informal hedges that flower/fruit on last year's growth

Most formal hedges require regular pruning to keep them in shape, so flowers and fruits don't have a chance to develop. However, informal hedges can be pruned selectively to allow a flowering and fruiting display. Plants that flower on one-year-old growth (e.g. pyracantha) can have the current season's growth reduced by half in the summer. This exposes the coming crop of fruit to its best effect.

Why prune