research

i hear stories of writers who spend years researching a topic before starting a story - who interview experts, read text books, etc... to absorb all the facts they want to put into their fiction.

other writers i know make it all up as they go along in the first draft and save the fact-checking for revisions, which i imagine can mean lots and lots of rewriting, depending on which facts they got wrong.

i think i fall somewhere in the middle - researching as i go.

for my current WIP, i had to do quite a bit of preliminary work, because i knew before i started that one of my characters would have Down Syndrome. i had to compile medical notes, research family dynamics and do a lot of observing.
it's probably the most research i've done before actually putting fingers to keyboard.

what happens more often is a situation arises in the story that requires me to know what i'm talking about. if i can see this coming, i'll stop, do a day of research, then get back to writing.
(example: i had a quirky scene that required one of my characters to know a little something about small towns and geography. i decided to make that quirk a thread throughout the entire story, but i had already used up the limited facts i knew in one scene. so i had to stop writing and spend some time expanding my knowledge base in order to pull the thread through.)

occasionally, i'll fall into the pantser category, when the writing is just going too fast and smooth for me to stop. who can be bothered with research when the facts i'm making up work so well?!
i don't let myself get too far, though, because i don't want to rewrite thousands and thousands of words all based on a mistaken fact. what i'll do is stop at the end of the chapter and do some fact-checking. then, if i got anything wrong, i'll fix it. but sometimes even waiting a whole chapter is too long.
(example: i had an entire chapter and plot development that hinged on a certain type of government office being open at a certain time of night and operating a certain way. i did some vague research online, but it wasn't until the chapter was over that i actually contacted someone at this office to verify my facts. turns out not only is the office closed and its operations nothing like i described - but it doesn't even exist in the town where i put it! (*&$%$&^#). i couldn't bear to rewrite an entire chapter in the middle of NaNo, but you better believe i spent half an hour typing up a list of corrections and plot changes in my revision notes. the good news is, the changes will make this little piece of plot better anyway.)

since that incident, i've been very careful to check my facts every step of the way - whether it's placing a building on the correct street corner or confirming a state law. but i'm still doing the research as i go, letting the story tell me what it is i need to look up.

i'm curious what other writers do!
*if you do loads of research ahead of time, how much of it do you think goes unused - and do you think that time would have been better spent writing? or do you think having the knowledge still makes the work better/more informed in the long run?
*if you're a pantser and later find a factual error that requires changes in 23 chapters, does it make your revision process more stressful? or do you prefer rewriting later to stopping and starting while in the middle of a first draft?