Just wondering how long everyone's first scenario was? I was surprised it took us about 2.5 hours. When the beginning said 90 minutes. And we didn't even look up many rules. Plus only with 4 investigators. I'm thinking the time is for 1 or 2 investigators.
We did have someone go insane which was fun.
Think it depends on how much of the flavour you take in.
Once you've played the game a couple of times you will know some of the attacks and get used to rolling dice, using items and so on.