Assuming you're well equipped and have buffer chars for 6.1 I'd dual hell ruins 2 with a friend, one side each while in group, and solo hell ruins 1 when 2 isn't available. For sp you'd want a WK 100 Atk rest element, although you can play with more ele/less atk, I consider that the optimal setup.
As for 6.2, you can solo it as scout(100 atk rest ele), killing 1 by 1 and using sader triple everytime it's up, this would be slower but much calmer as no one is likely to go there and you can watch videos or stuff meanwhile, you can also try to lure either solo or with a mate, the best maps for luring would be ancelloan 3 and 6 because there's an increased number of mobs there, and for luring you'd want a WK (pointed the same as for 6.1).
If I had to say a number I'd say it takes 35h more or less to go from c30 to c50. The choice of map is up to you, 6.2 mobs do hit harder but if your equipment can handle it go for it.