Grip failing on deadlifts

I'm OK if I have to do 1 or 2 reps, even with heavier weight. But if I'm doing sets of >6 reps with atleast moderate weight, my grip goes to shite. Even when incorporating almost 5 second pauses in between reps, doesn't help much.

I'm trying to stick with conventional style grip. mixed grip always ends up making me favor whatever side has the under hand. Would prefer to just pull the lighter weight conventionally for now until the grip catches up instead of resorting to straps.

I've started doing holding kettle bell holds/walks, hanging from pullup bar, focusing on maintaining tight grip on pull exercises. For the past month I've been focusing on grip about 3 days/week, seen some improvements but feel like its been minor compared to the amount of grip work I've done.