Current studies indicate you need at 10-20 sets per body part per week to maximize growth. I don’t remember whether that was going to failure each set or what % of 1RM each set was, but I keep that number–10-20 sets–in mind when I set my workouts. If you do a 5X5 routine for each body part two or three times a week, that should do it. For me, I have to do chest three times a week or I go backwards. It’s my weakest area. So that may be what you have to do to make your lats pop. No expert here, just a suggestion. And again, you already look great!