How do heroes handle hex stacking?

Are heroes smart about stacking hexes? Will they purposely recast a hex if a foe already has it? For exampe, Wastrel's Worry and Icy Veins recharge shorter than its duration. Would a hero reapply the hex if it hasn't worn off yet?

Heroes won't use a hex on a target that is already hexed with the same spell, or at least I've never seen it happen. This includes renewing the duration. They'll wait for the hex to expire before they reapply it. As for Wastrel's Worry and Icy Veins, last time I equipped those on heroes, the heroes would spam WW on recharge on multiple targets, quickly depleting their energy. They tend to wait to cast Icy Veins until a target has low health.

Heroes know that status of all enemies and will never cast a hex on an enemy already suffering from that hex. This is the same behavior with enchantments.