This is from the perspective of someone that has a decent amount of play time each day 2-5 hours a day I personally don't think enhancement cores should be involved in infusion unless you drop the cost to 1 these cores main function should be to master work gear and weapons. I haven't had the opportunity to do this to any of my gear since year 1 because each piece of desireable gear I obtain I try to infuse into max light which leaves me with no cores to master work. Another option make spider sell cores for a standard price of 20 legendary shards.