Wow I just did the math to see how long it would really take if you went from start to finish with no stride for puzzle 66
With the start and end params of 20000000000000000...3ffffffffffffffff and a 3080 at 1100 MKeys/s or 1.1 billion keys a second
I got
33,539,534,679 seconds
558,992,244 minutes
9,316,537 hours
388,189 days
1,063 years