"Ski Wee Herman" 
Every 2 Minutes for 28 Minutes 
300m Ski 
Even Rounds: 30 spm or lower
Odd Rounds: 36 spm or higher

Aerobic effort with built-in breaks and alternating objectives through spm recommendations. Always an effective way to keep you in the game for the full 28 minutes. Was able to stay pretty consistent from round to round, even keeping the lower rate rounds within 4 seconds of the higher rounds at the same damper setting.