Those look like air roots to me and are usually very fine.

Waiting for stems to callus helps to prevent possible rot from too much water. You don't have to wait too long for callusing especially if the stems are quite thin and the cut is 'clean' - without any fraying of tissue, or being squished (could happen if the cutters/knife were dull. Many ppl use a blade for this - not absolutely necessary.)

"You don't have to wait too long for callusing especially if the stems are quite thin and the cut is 'clean"

I'm curious Rina-would it work if one put cinnamon on the cut end to help speed up drying of the cut?

Cinnamon would only help if it were previously rotting. In this case, the stem is so thin that 1 day would be enough for it to dry out completely. For succulents with stems many inches thick, sometimes it takes weeks or months for it to dry out completely.

I think humidity also affects how quickly a cutting callouses. Dry location with good circulation is good.

Agree with Garrett and socks. I used cinnamon, but only if I am making cut of larger diameter, like jade, and use it sparingly.

Thinner the stem, less I wait :)