What if I can only do one?

Put the weight anywhere you can! 

Saturday's workout included 6 rounds of max rep strict pull ups in a minute (along with other movements). An athlete who has just recently achieved her first strict pull up asked "what should I do instead of pull ups?" My answer to her was to do one or two strict pull ups, not to substitute them for ring rows or jumping pull ups. She was able to get two pull ups each round, which is probably more pull ups than she has ever done in a single training session before. That makes for a great workout, and will improve her strength and endurance in that movement. The trading stimulus she experienced doing those two strict pull ups was probably pretty similar to other athletes doing 5-10 per minute.

Had the workout been 21-15-9 reps of pull ups and power cleans, I would have had her substitute in a different way. Options here would include less pull ups (12-9-6) while still doing 21-15-9 power cleans, or possibly performing jumping pull ups or ring rows if we felt like she could sustain the pull ups. 

Scaling is more of an art than science. Make sure to ask for help when you scale and try not to get locked into one way of doing it when you do!