yup, timpani always uses single stroke rolls.

Another way to work chops (as I have taught others since my days in high school) is to take your timpani mallets in your hands, reverse them and stroke out the single strokes upon the meat of your forearms.

At first, you may hit the bones along your forearms, but that forces you to play the strokes correctly as you drive the force of the mallets with the last three fingers on each hand.

Do that for ten or fifteen minutes each day by watching TV or a movie and you will have the singles chops you need to perform!