User blog comment:ImperiexSeed/Supernatural Mysteries/@comment-3481504-20120404154634/@comment-3045936-20120408203613

Ash said that Sam and Dean went to Heaven several times. So when Sam was first killed off, in the end of season 2 his soul went to Heaven and was revived by a normal crossroad demon. The Salute to Supernatural season 6 said that sam's soul never went to Hell until he jumped in the hole in Swan Song another prefence that Eric made each brother goes to Hell once. (If you don't count, Gabriel time loop deal in Mystery spot._ Hell is a prison, Heaven is a paradise as to how idk but Eric Kriple has said that reviving from hell in Salute to Supernatural Season 4 after Dean was resurrected is far harder than being dragged down from Heaven his own personal idea and reason for the introductions of the Angels.

I guess that based off it takes a lot of good to leave Hell and rise to Heaven, compared to how much evil it takes to go to Hell.