My first play was very difficult, and I failed many quests... I beat the game using drugs, A LOT of them !! I remember that after the final boss I was dying because of the negative effects
but yes, required 6 hours...
(If you speak with people you don't have to explore too much... the locations just pop up in the map...)
The second one was a little less, like 4 hours but I maxed out everything (also advanced power armor and turbo plasma rifle) and every "good guy" secondary quests (brotherhood, the city with the gangs made peace, deathclaws, etc... etc...)
The sniper with plasma weapon is the easiest and fastest character to win, it is able to 1 hit kill EVERY super mutant, and with the right perks you can kill 4 of them every turn
I also tried the melee way, it's VERY difficult at the beginning and there's ONLY a weapon that can change the story, the super sledgehammer of the brotherhood of steel !!
Once you have that, the power armor and a LOT of movement points, you can start first in every combat, and while you don't kill easily with one hit, you still can break the arms of 3/5 mutants in one turn (depends on the distance), making them unable to use weapons, and then kill them the next turns... they are unable to make too much damage bare handed...
It was the funniest experience, because they were flying away at every hit