How much should I prep for a session?
This is a hard question to answer, but I have a short story that illustrates how a tiny amount of prep can go a very long way. In general, I will spend about 2 to 3 hours preparing an adventure. I always think that the players will get through it in a single session or two at the most; but, that is never the case.
A Practical Example
I spent about 3 hours numbering the various areas of the map shown in the Resources section and coming up with descriptions that fit with the campaign. In total, there were 13 encounter areas. My handwritten notes took up about 3 pages of a typical college-ruled notebook.
So, how far will all that prep take us?
Session One (3 hours with snacks and drink breaks)
You can read the campaign diary for this session here: Runs of Alderwach Part 1.
The party managed to complete on combat encounter and explore the main hall. They encountered the main puzzle for this dungeon but split the party so half could work the puzzle while the other half backtracked to explore some of the dungeons they had passed over.
Session Two (2.5 hours with snacks and drink breaks)
In this session, we focused on the half of the party that had run deeper into the dungeon: Foodie, Brilgar, and Lilith. The other players are scheduled for Session Three.
You can read the campaign diary for this session here: Runs of Alderwach Part 2.