Fanfic planning; a rant tbh

Okay, how many people actually plan their fanfics out? Most times I'm just absolutely winging it and if my brain has an idea then that's what gets written. Though this new fic I'm planning, mostly cause I need to research a lot of info for it. Some people just plan all the time and I wonder how they do it. My motivation would be gone so fast. 

I'm over here gonna be researching two different cultures and what they do during specific 7 months. This is gonna be a lot to remember and half of it I'm not gonna be able to use.