If you're going to be a writer of any kind, you have to research. No escaping it. Fail to and a reader somewhere in the world will catch that one inconsistency and call you on it, and for them, because of that oversight, the story will most likely lose credibility. You may even lose them as a follower, not something to dismiss with a pshaw in this new age of immediate entertainment gratification.
Recently I had one writer tell me that she knew all this historical information because of her long experience as an amateur re-enactor. While involving yourself in these often pleasant and invigorating hobbies you can learn a great deal, but unfortunately much of it can also be hearsay. I can remember well the raging debates among 18th and early 19th century re-enactors regarding the ubiquitous uniform many women seem to wear, as in bodice, petticoat and mob cap. Despite a cascade of primary source documentation that clearly refutes this olde-timey costume, many female re-enactors refuse to capitulate to the proven attire solid research would dictate.
Equally, as a writer, I am incensed when we fall into the classic error of the bodice-ripping scene in a historical novel set anywhere from the 16th century forward. Clearly the writer has no knowledge of historical garments, otherwise that brawn Fabio hero wouldn't be able to shred our heroine's bodice from her heaving bosom.
What we'd actually experience is a laborious, potentially sensual, removal of layer after layer, starting with a tightly fitted laced or pinned bodice which may or may not have laced or pinned sleeves. If she's middle to lower class that bodice may be what's known as a short gown (think jacket). Perhaps there's a stomacher pinned in place, then a corset or stays which may be laced front or back or both, and depending on station in life and era may be boned with up to 180 whalebone splints (veritable armour) or if she's lower class may be stiffened with cording or reed or may be constructed of just of heavy, plain leather. And it's important to note that the corset or stays were considered underwear, and so to have a woman swanning about in public in her stays would mark her as insane or practicing an age-old trade.
There would be an over petticoat (what we know as a skirt), usually tied at the sides, likely an under petticoat, perhaps hoops (also known as farthingales), perhaps another petticoat. Finally we're down to the chemise, which often was worn as a bed-gown, and then depending on the era, there may be drawers, and depending again on the era, those drawers may be bifurcated.
Even during the Regency period (also known as the Empire or Federalist period, with somewhat malleable dates depending on region), there were layers to part.
Our hero would have to work for his lady's gifts.
And this is but one example. From foodstuffs to geography, hygiene to transportation, you have to know your subject.
I remember clearly a reader questioning the use of a brake on a medieval wagon. Indeed there were brakes, something that consisted of a block that could apply pressure against the wheel through a lever operated from the driver's seat. I also remember being brought to task in another novel when I sent the manuscript to a colleague for comment pre-publication. At issue was the transportation of a moose carcase. I had my hero dragging the kill through the forest, never even giving thought that this beast could weigh up to three quarters of a ton. Oops. A quick rewrite of the scene corrected my lack of research and the credibility issue vanished.
Being a writer means you should divide your reading time between non-fiction for research purposes, and other reading for your own pleasure, although for me, the research is often an adventure and a joy.
Why do all this research? Aside from keeping your readers reading, a solidly researched novel can, if well-written, add to the richness of your story, create an entire surround in which your reader can immerse and become enthralled, thereby keeping him turning the pages, and resulting in a follower who will watch for your next novel and recommend the one he's just finished to his friend. And so it goes.