There is a very big difference between creating a quest by working with all the frameworks previously developed by the companies who did the base-game, and then doing everything from scratch with a really, really small team.
Every single interaction from when a character collides with a trigger to when it activates a cutscene, then having someone to write that cutscene; getting voice actors to voice what they say on the scene; then listen to all the audios and see if everything is okay and then manually splitting, one by one, both text and audio (That can go over 40 minutes of over 4 pages) of all the sentences to put on the dialogue widget and make everything work inside the unreal engine. Then creating the events that will happen on dialogue from scratch (will lights turn on and off? Will character equip or unequip a weapon? Will a different camera angle happen, and if so, place the new camera there. Will the character play an animation while she talks? if so, do you have that animation already or will you need to animate it yourself in blender?). Then you pick all this and make it work on the level design that your team is also doing from scratch by placing all the objects that need to be in that area, interior and exterior. landscape and even modifying LOD (level of detail) of models so they don't cause too many issues on the performance. Then you need to make this all work with the games\load system and test, retest and see if players can make shortcuts to trigger events that could only happen at another point of the quest.
All of that while in the background you need to reply to emails, check comments on the internet, engage with your public and make sure that you are doing your best while also taking care of your health. Because 3 months ago you had to do a lot of crunching to get a patch with the new stealth system work in time for the new release but then you completely fucked up your arm and had to sit back for a while, trusting that the rest of the team would lay the land for you once you get back to your feet, which I just recently got.
You do all that in a month, make a release, then repeat. Now if after all that, and under all that pressure you still believe that you would be able to deliver 4 quests per month, we would gladly want to have you on the team because that's an impressive speed of work! =D
After all, the donations we have been receiving from our wonderful supporters are finally allowing us to reach a point where we are seeking to expand the team so we can speed things up.