Windswept:
I am not telling anyone what to do, just expressing an opinion. I agree that the walk can be done in 21 days. That said, in my opinion, the walk would be more enjoyable at a slower pace or shorter route based on time allowed. I applaud you on your Camino and the cause for which you walked. Someone also did it in 9 days.
If one would want to stop and smell the roses, visit sites along the way, spend some time with new acquaintances, deal with injuries or just choose to take a break a slower pace might afford them that opportunity.
I offer my opinion of a slower pace on a shorter route as an option to your recommendation, not a mandate.
Ultreya,
Joe