That was an interesting topic, more than I might have guessed.
I take two poles if there are any ups and downs worth mentioning. Although on a little local mountain I do frequently (2 miles 2000 ft. gain to the top) I take only one pole for some reason. It has been shown that they increase your efficiency (that means improve speed and endurance, I suppose). Much like Jesus, Many years ago, I used to find a stick about the right length and use it as a walking staff. Once or twice I have climbed or traversed a steep snowfield w/o ice axe and I know how to use poles to arrest a fall so I felt much safer. (would not crossed it, them, w/o an axe or poles.) I am 78 and have an arthritic hip (replacement scheduled on Christmas) so I definitely like two poles to take a little weight off the hip.