Except in a few exceptional circumstances this is surprisingly not the case. People drive at a speed they perceive as appropriate for the design of the road. Wider roads, wider lanes, straighter roads, open sightlines, and bigger shoulders will make people naturally settle on driving faster. This is why just blithely reducing speed limits with poxy signs on problem roads famously doesn’t accomplish anything. It’s also why people go bombing down the stroad in your local commercial district at 55+ MPH in complete contravention of all the signs everywhere that probably say something around 35. The damn thing looks like a highway to peoples’ monkey brains, so they treat it as such.

People certainly talk about how “my strategy for speeding is to take the speed limit and then you can go around 5/10/15/whatever over and the cops probably won’t care,” and if you sit there in the passenger seat and actively press them on it they may actually drive that way for as many as several consecutive minutes. But most of them just fall back to their perceptual “intuitive” speed for whatever road along with everyone else. Especially if they see everyone else passing them.