There are just so many ranges on Puzzle #66 that its near impossible to solo.

Stats from ttdsales pool below in my sig.

Total Ranges Checked: 92,272 of 33,554,432
Total Private Keys Checked: 101.45414 Quadrillion
Percentage completed: 0.274992%

the ttd pool is using a customised vanitygen for cracking, source is available in the files on the site. seems to work quicker than Bitcrack. Worth trying out even if not with the pool, I found big improvements on the 2080 Ti's and 3070's not as much on the 3090's but still faster.

http://www.ttdsales.com/66bit/index.php