I've yet to work on a larger project that requires any genuine amount of research, though there isn't a thing in the world that can be written without consulting somebody, or at the very least Google, several dozen times.
Even when you're writing in a world of your creation, getting just the right word, the appropriate detail, seems so important. Fantastic worlds still need to feel genuine, and sometimes being sure you've referred to a certain architectural feature correctly, or haven't totally fudged the beer brewing process, feels vital. Your character knows these things. Shouldn't you, too? How can you talk about something you can't quite put your finger on?
But more importantly, how to keep from falling down the rabbit hole and getting sassed by the motley collection of doped up caterpillars that is the internet?
Writing is tricky. Sustaining a habit of writing is even trickier. Part of my writing process has always been leaving what I can't answer immediately, or within a few minutes, to be handled during my first round of edits. Editing is a big job, but I feel less pressure when I'm editing because at least I've got something to edit. I want to run from the blank page a whole lot more. If I stop and dither about with looking things up or finessing the details, I run the risk of falling out of the narrative. So if I can't remember what that fiddly bit crowning a castle is*, or I don't know what sorts of things besides hops go into a beer, I make a note.
And I keep writing.
Some folks might get hung up on not knowing and won't be able to continue writing, but me, I'm always looking for any excuse to take a little break (the curse of learning to multi-task too well, I think) and if I ever want to finish anything, I just can't.
Side note about notes, mine are easy to Ctrl+F when I'm editing because they're always the same. I use XRUMBLRARX mostly because it is extremely silly but also because even if I only type up part of it, the letters aren't likely to appear next to each other in anything else.
What works for me I certainly can't imagine would work for everyone, but at least there's a little levity in my ignorance.
*I guessed this and I was right: it's crenellation. Score.