Cooldowns should be several hundred meters at least!?

The Science Of Swimming Faster book makes a strong case for "long cooldowns", at 55-65% of your max speed. The writers argue for 25-35min of easy swimming after a short race, or an intense speed session, and 15-20min of easy swimming after a longer race, or an endurance session. I'm convinced to do 800m always now, at 14-15min. I enjoy it. Many other books offer a 200m to 400m cooldown set, without much rationale. I enjoy looking at the workouts of some of you "real swimmers", and I often see "100 easy" to cap things off. (No names!) Would you recover better with a longer cooldown? Thoughts?