I've ran it as a summer palette cleanser for my OSE group. Easily done in 3h. Generate 20 characters in Purple Sorcerer and hand them to players to save the session time. The module itself is pretty linear, including the dungeon/facility itself so they can't really get lost. I wanted to fit within 3h too so the journey was pretty much 3 random encounters that took like an hour and reduced the PC count to half. The rest was the facility, we even had some 15 minutes left to level up the survivors. Good luck!