You can use this shuttle variation to work on metabolic conditioning, especially for defensive work:rest intervals in ultimate. Going short-med-long-med-short-med-long-etc, run for 40sec, then walk the pattern for 20s. Do three 40sec bouts per set. For the 2-3 min rest between sets you can stand still, sit down, get water, etc. Increase intensity each set. Use a loud timer or watch to keep track of time. This form of doing shuttles is great in groups because people of varying speeds can all complete the work together and get the same metabolic benefit at the right challenge level for them!