The question here is fourfold but I will be brief for now as I do not want to muddle the discussion with a lot on methods, math and such. One, how much time away from computer do we have? This is time on task. Two, how much time do we actually spend in game? - This is Time at task. Three, how much time can be saved by a more experienced player? Four, how #2 compare with the Devs time estimates. One, there was about an hour spent doing stuff like going to restroom, feeding the fur babies, selling stuff, upgrading equipment, etc. and that means my Time on Task (or total time spent at computer) is about 9 hours. Two, that means time at task (or time spent actually gaming) is about 8 hours. Three, I was able to get the time down to 4.5 hours of game time by just skipping cutscenes and dialogue with frequent interruptions (like sleep, try to kill Ashava) but you will still lose at 30 minutes to feed the dog, etc. but you might be able to just do a straight 4.5 hours if you don’t have other people or animals to worry about. Four, Mythic Drop stated that it was 35 hours to level 45 and I am at a pace to do it in 28 hours and 28 minutes. That is 6 hours less time. It is just over 8 hours to get to level 45 if you skip cutscenes and such.
A couple of quick notes. One, it would seem that a person totally unfamiliar with the Diablo Franchise might tale 150 hours to get to level 100. This means spending lots of time looking at skills, comparing gear, etc. and that takes up a majority of the time. If one counts looking at videos, checking forums, etc. before playing the game, it may take an experienced player 150 hours to level to 100. Two, skipping the cutscenes, dialogue saved over 40% of the time. However, that number was down to a third before the final two areas. Since they are dungeon heavy, there was not much that could be skipped and that brought up the percentage.