Q: My question is why when after you've reduced liquid you add more liquid and reduce again sometimes multiple times. For instance I was watching Anne Burrell making a bolognese sauce. She reduces it, adds wine, reduces it again, adds water reduces and repeats the water additions and reductions multiple times.
Also, many reciples call for adding wine reducing then adding stock and reducing. Why not add it altogether and reduce once?
A: I wish I knew the answer to this - maybe it's because their pot isn't big enough. Science and common sense tell us that these steps would be nearly superfluous. And deep down, I completely agree.
Adding water to simply evaporate it back out wouldn't seem to affect anything but cooking time, and it doesn't seem as though reducing a liquid in (or not in) the presence of another liquid would change the flavor or manner in which it reduces.
BUT . . .
There are instances where I concede to what I call the "grandma factor"- this is when some ingredients, or cooking step that makes no sense at all is called for in a tried and true recipe. Bolognese certainly falls under the category of dishes inherited from another generation - along with chili, beef bourguignon, matzo ball soup, etc. etc.
I know this doesn't really qualify as an "answer" but maybe it helps you understand the question itself a little better.