You’re misunderstanding. War bows can’t be held, the bow is way too heavy to allow you to hold an arrow and loose it at will; drawing and loosing are two actions of a singular movement.

Volleys were used, but the similarity with the way they’re used with firearms only exists in the use of crossbows, which were invented specifically because they allow to draw and shoot in two motions (and also they require virtually no training compared to war bows)