I think it's real science and known to work, but the devil is in the details. Experts will have specific training plans tailored to individuals, and sometimes advise general plans, and the rest of us take it as gospel and argue and advise amongst ourselves and those details of individual differences get lost.

I've never ridden a recovery ride. I've no idea whether that has helped or hurt me, but I'm pretty sure that embarking on a formal training plan, I'd need the scheduled recovery rides.