Simple calc
Any report bitcrack or similar when u set from end bit range it's tell u how much time, resulted multiple thousand years,
And actually you see difference from 67 to 69 within 1 year 3 keys found , and most some individual with 1 or few one GPU, it's mean clear your thoughts not calc
Simple using these gpu with formula or strategy can reduce multiple years to few months,
As I stated before 71 puzzle could be found with 1000 gpu max 7 days...
If you have less GPUs you can try to find puzzle 135 with my strategy,
It's not mean