You know what I do when I’m pulling heavy singles or hard sets for reps, I put liquid chalk on my thumbnail. My grip started to slip a couple times when I was doing heavy rep sets, I think they were sets of 5, my hands were sweating too much and it seemed like sweat was squeezing out on every rep. I never actually dropped the bar, but when you’re struggling to hold on it’s hard to actually pull and seems to inhibit other muscles. Anyway, I had a bottle of liquid chalk laying around from when I used to train in a commercial gym and I gave it a shot, haven’t had grip issues since.
What I mean about cutting your thumbs to fit the glove is that you should be using whatever equipment because it will benefit your technique, leverages, etc. It makes no sense to buy something and then make your body conform to it. When I first used heeled shoes I had an instant increase in weight on my squat.