It’s alot of work researching a documentary, especially as there’s always a few ideas being fleshed out at the same time. One never knows if someone else is planning the same thing or if it’s just to costly, or even possible. It’s been said to prepare for any story you must call all your references or notable voices, hopefully authoratitive to add strength to your story or script, heck anyone. I know from personal experience outside of film-making that cold-calling works! Part of this planning includes actually shooting with new gear and situations.