Most xp not affecting mending tool.

When using the mending enchantment with any source of xp(experience) such as furnaces, mobs and most significantly xp farms such as skeleton farms the majority of xp orbs gathered go to the hot bar and not the enchanted tool a player is holding.

This results in mending being essentially useless for everything but a fortune pickaxe as tools take almost an hour to repair to full.

I've tried taking all armour off and just using the tool but most xp still goes into the hotbar xp rather than the tool.