Are you brute-forcing using a paper? How many keys per... ehm... day?
I can brute the last 12 digit for 3 hours in 3080
I have 6x 3080. So every 3 hours i can verify 6 guesses that i wrote on papers😅
Puzzle 69 start with 1 so im guessing 6 hex after 1
Every day i verify 18 guesses , i change range manually 🙃😅
so make yourself a simple script that will automatically change ranges, and it will be easier for you)