I can't tell how much time, but I do use various sources in order to describe the clothes accurately and present the traditions and customs as they are/were. I used both physical books, and various websites that were recommended to me. Representing the mythological creatures and how they are seen takes a lot of research as well.
I also try to post links, if I can.
I do far too much research. My novel is a fantasy but with 1700s technology so a lot time has gone into looking into how the weapons work, how accurate they were, and other bit of technology. A huge amount of research has also gone into everything to do with sailing ships of the time because that's a big part of my story, getting the terminology right and how it feels aboard one, that kind of thing 
I also spend far too much time researching the meaning of names but that's a whole different story!
Waaay too much time spent researching my debut novel 
It's set in 1990 - but still an historical mystery, so mega important to me that I made it totally authentic. With hindsight I should've only begun the research once I was one or two drafts in, but I love that stuff and .. well ... you can guess where dozens and dozens of unnecessary hours went ...
My comic is based on astrology, it's my hobby since childhood, so I guess I research my whole life, lol.
Probably a lot. I read a full-length book on Byzantine history, listened to another audiobook, and a few podcast episodes. (I also read a little bit about the Varangian guard, but I found myself in a hole of information that isn't super relevant to the story, so I saved the book titles to read later in my spare time.)
I've read a lot of articles about fashion, armor, and where fabrics came from. And architecture, and I've looked far and wide for good books on daily life for byzantine peasants (Had to use the interlibrary loan services so I couldn't read the whole book - I could only had it for a week!)
I like researching, it helps me get ideas! If the people living there had a specific thing they did, or found a certain ritual or omen to be important, then that's fun to use both for plot and for subtle symbolism!
I've done a bit of research on psychology and cognitive therapy as my MC is a kind of counsellor in her universe. I have a friend studying as a counsellor so sometimes I pick her brain about it too!
Not really. It takes place in 2016 and it is an outsider’s looking in, so they don’t pepper their speech with Italian. I only have one sequence where two older family members speak Italian to create a bit of a mystery. I do not speak Italian, so I didn’t feel like overburdening the google translator.
There is a few scenes with a little bit of French that are de Sade related, so I am more comfortable there because I have at least a dim recollection of French.
But I am not big on the guy going mi amor, this, mi amor that if he is the third generation.
There's not much of "research" for my fantasy story honestly, but I do collect background/tool pictures when needed for references. How much time? I don't know... Other than that I watch some writing advices/mini seminars, or manga drawing tips from YT channels sometimes.
That is true. I can barely understand italian since it vaguely since i speak spanish so i recognize some of the words. XD That and i watch an Italian Youtuber called ThePruld who does all these funny vids and im slowly learning italian from watching him. The only language i mostly research upon is Latin because in my story the characters cast spells and they're in latin.
Aristocrats names sometimes sounds so weird to me. XD but i have to research some of them because there are some Aristocrats in my series.
It's just clockpunk (a world where all the technology is based on gears and springs and Da Vinci-esque designs), but not very advanced yet so it's mostly lurking in the background.
I don't do too much other than maybe googling pictures for inspiration or just checking to make sure something is actually plausible before doing it. Once had to research how long a person can go without food for a character that was going to be locked up. Little things like that I'll do quick searches. For the most part, I let my first draft be whatever my mind wants it to be. I have some leeway given I write fantasy so I can get away with making a lot of things up though I do know I have to keep it somewhat grounded in reality. I'm what you might call a lazy writer. I enjoy the writing part more than anything else, so the less work I do to get that first draft, the happier I'll be LOL Now if I ever am going to publish for real, then I'll spend more time on things that probably should be researched more (such as sword fighting stuff that I have zero knowledge of yet always seem to involve in my books somehow LOL) and take a lot more care into it.
I research until I am comfortable that I can write something without being totally ignorant about it. Usually, research will continue throughout the writing process. I can't prepare for everything so if I end up changing a scene or a section of the plot, then I may need to do more research to account for it.
I tend to research a lot. I don't want a reader to be completely pulled out of a story because they are thinking about how I clearly didn't research something 
I will never avoid that completely, but I'd like to minimize it.
Plus, I enjoy it and it can inspire some need ideas!
that i never knew.
