Heavy cavalry tended to be problematic. It was usually rather well protected and bore right down on you, unlike horse-archers who normally kept their distance. Actually checking the charge of armoured cavalry by sheer weight of archery alone was apparently a rare achievement, and spoke of fairly awesome degree of training among the troops for the necessary rate of fire to be achieved. Mamluk horse-archers (possibly an elite unit) apparently pulled it off at least once against Crusader cavalry, but that's about the only instance I know of.

Still, distrupting the charge to the point where it loses much of its effect can be achieved with less heroic feats of nocking arm. The English longbowmen managed it often enough (although the horsemen still needed to be chases off the old-fashioned way), and by all accounts they couldn't hold a candle to the Easterners in this field.