Yew can be pruned just fine and has the ability to re-form new shoots on old branches. To keep clipped forms and hedges nice and taut, 2 pruning sessions a year are necessary. The first pruning around mid-June, after the first growth peak. In September/October you can prune a second time so that the plants go into the winter taut. Pruning is best done in cloudy weather to reduce needle burn. Taxus can also be pruned once and is usually done in August.
Yew forms are best pruned with ordinary hedge shears. Do choose quality shears so that pruning remains an enjoyable job. It is also important to keep the blades razor-sharp.
TIP: If you prune in wet weather, you will not suffer from deposits on the blades so that cutting is easier. Regularly cleaning the blades with a wet sponge gives the same result and you stay dry.
Hedges and massifs are best trimmed with electric or motorised hedge shears. They allow you to "shave" nicely and maintain a straight line. If the blades are kept sharp, leaf damage is not too bad. You can also work much faster with these devices than with hand shears.
Drastic rejuvenation of an old hedge or clipped form is best done in winter. This will give the plant the opportunity to produce new buds in early spring and sprout again. It may take some time before the plant has fully recovered. Extra fertilisation is definitely recommended.