Millions of people experimented with food, many thousands got something interesting and passed down the technique of how precisely they did it. Exact measurements aren’t usually necessary if you manage to do the same things the same way as the original author.

Generally things like this were discovered through trial and error, being done by LOTS of people, in many different places, over a LONG period of time. Pre internet, pre movie theaters, pre entertainment, people had a lot of free time, and not a whole lot to do with it, and so they tried making stuff to see what would happen.

Another thing is that until recently, a lot of things that require exact temperatures or demanding environments simply DIDN'T get created.

Caves helped a lot to develop cheese making. They are ideal as their temperature and humidity are relatively stable.

Someone else already mentioned caves, which have very stable temperatures overall.

I'll also add that temperature stability is one of those things that scales with mass. 500 grams of water/milk/cheese/whatever will have more variation in temperature than 50 kg of the same substance.

So cheeses were usually made in really, really big wheels, because that way the temperature would be more stable throughout, and then they'd just cut pieces out of the big block.

Or they only got created when weather permitted. It parts of Germany it was illegal to make beer during the winter because low temperatures make the ferment inconsistent and unpredictable. You had to make all your beer ahead of time and store it. Candy is similar- high humidity interferes with evaporation of water from the sugar, making it sticky. Many people don't make candy before or after heavy rain or storms.

Agreed on most of what you said, with a small correction: that people today have more time and can watch movies, entertainment, etc, because of advances that freed our time. Previously people used to spend a lot more of their time finding and growing food, crafting stuff, etc, mostly during daylight before electricity enabled people to see brightly at night. (so people also probably slept more too)