Jelqing in Sets

While jelqing, I get less than 80% erect after about 20-25 strokes, which means I have to get it back up. Is this normal??

It leads me to wonder if any of you guys just go ahead and jelq in sets.

Um I jelq at a fairly level anyway, but when I feel it subsiding I speed my jelq strokes up a lot and use my imagination more (on a porn detox) but speeding your strokes up I find helps.