I'm currently boosting my teams from 1 - 46/90 and with RAF bonus i use about 3 hours to get them up to 46.

I'm running Dead Mines 10 - 20, The Stockades 20 - 31, RFD 31 - 35, RFK 36 - 46. *3 hour mark
At my first team I also did Sunken Temple 46 - 60, Blood Furnace 60 - 68, Nexus 68 - 77, Blackrock Caverns 77 - 85, Temple of the Jade 85 - 90. *11 hour mark.

Without RAF the times would be about x3 i would imagen. So 1 - 46 9 hours, 1 - 90 33 hours. Not sure how much time you would spend lvling a team from 1 - 90 dungeon spamming, but I think it would be faster rather than boosting the team with a single character.