300 people can do more then 1 act in 1 month. You can make all of act 1, 2 in 1 month if work flow is done correctly. I made a 50 map pathfinder campaign [urgir, Mandev, custom city 4x size of bg3, level 16, the entirety of the land of mammoths, in less then 2 weeks myself using solasta game engine DM maker. People think it's hard... it's not. Only reason there is so much missing content is because the devs where lazy to complete it.