Not sure what you're claiming, but SPM and stroke length isn't a measure of how much work you are doing. For instance, you could have the exact same SPM, stroke

Not sure what you're claiming, but SPM and stroke length isn't a measure of how much work you are doing. For instance, you could have the exact same SPM, stroke length, and damper settings, and row either a 3:00 or a 2:00 500m time.