Im posting relistic feedback I test runs out daily , will talk about paragon lvling guide
Grift 48-53 = best exp for most barb ( 40-50 ww runs faster if you have decent ww gear)
grift 53-55 = Good exp if all ancient that are good and if ur paragon lvl is high
I'm currently running 56-57 for gem upgrade but its not as fast exp as 53-55s I use alteration when i do 55 + where i change all armor gem to diamond (But i still use red gem + leoric since i have good bracer of first men) and esteric gem
56-57 for me with these build which my gear are almost all ancients perfect ( played barb only from paragon 300) but anyways idk how he runs 6 min grift 57s... as i average 9-11 min average. As barb build tester id like to see
what alteration you are doing compared to mine that can boost time so much since my gears are almost all perfect maybe ur paragon is like 1500s =)
Just to give basic items stat i have
20/100/9 hellfire ,
950/900/50/10 glove
987/910/15%hamer helmet
622/636/15% hammer
20%fire 621/598 6crit (197 hammer dmg) first men bracer
640/620 ik belt
648/649/14% life ik chest
621/650 ik pants
620/610 /15% life/ 20%area shoulder fury of ancient
6/50/6 focus 640/50/6 restraint
4287 1398/1340 38% increase hamemr dmg
Gems = taeguk, pain enhancer, estrotic ,bane of trapped lvl 70s all .
Now i know its not PERFECT but this is fairly high end barb gear with paragon 990s but w.e. you are doing 6 min amazing for 57s =)