Hello SoulDoc,
I agree with you: a complete fast should only need to be done as a once in a lifetime health-measure, but there are occasions when the body has not had sufficient time to heal, and would sometimes require a subsequent fast or fasts to maximize healing and cleansing.
It is the opinion of Dr Keki Sidhwa, one of the most experienced and longest serving Natural Hygiene Doctors, to fast for 7 to 10 days once per year as a prophylactic against disease, and as an internal house-cleaning measure because of modern pollutants.
I would totally agree with you that fasting should not be a way of life, but more of a kick-start to a new life, and with proper living habits thereafter, should negate the need for this on a regular basis.