Cleaning records. How often really?

Stop scrubbing Bill! According to Last, the preservative bonds to the vinyl of the LP at the molecular level. Scrubbing won't reverse that permanent bond.

Oh, wait a minute Bill. The Last Preservative is not designed or intended to remove the mold release agent (allegedly, if you prefer) found on new LP's. Nitty Gritty at one time offered a product named First for that purpose, but it's no longer available. The Preservative is to be applied to an LP after it has been completely cleaned. I don't know how widespread your opinion of the product is, but as always, better to error on the side of caution, especially when an application is permanent.

Does anyone have evidence that mold release compound MRC is used in the manufacture of LPs or CDs?

Bill, it is my understanding that all records are pressed with a thin coating of a mold release agent applied to the stamper. If the stamper is not so treated, the LP's resist detaching from it after the cooling phase of pressing.

This seems to be true, but according to what I've read on Vinyl Engine, not every pressing plant uses it, and if it's used, it's a judgement call by the operator on when to use it.

Release agents are used for tool and die parts in manufacturing, wherever parts are being molded.

Effischer, ideologically I share your view even though I called it 'insane approach'. But I think this would be too much work and very inconvenient arrangements for me. I will machine clean the records I play after 10-20 plays or every year. And of course I will use Last record preservative. Every serious audiophile I heard of does it. There are also records that I don't play, they are for archive, I will clean them every 10 years, maybe. I keep copies of a few albums for future generations or if there is an accident and I lose my playing copy.