Cleaning records. How often really?

Reasons to wet clean a record more than once include:
1. the initial cleaning was inadequate; or
2. the record was re-contaminated during playback or storage.
Compulsiveness aside, there are no others.

To avoid #1, clean each record thoroughly the first time (to whatever standard of cleanliness you prefer).

To avoid #2, play and store cleaned records to avoid re-contamination. This would include steps to:
a) remove dust;
b) reduce vinyl's propensity to attract dust (ie, static); and
c) shield the record from dust when not in use.

I have my methods, developed over many years and after many trials and comparisons. My standards are high but my tolerance for re-cleaning is low. Therefore, every record sees an extensive cleaning, playback and storage regimen.

It works, at least for me. I'd estimate that 90-95% of the records I clean do not benefit from a second cleaning. OTOH, a similar percentage of records "cleaned" by friends do benefit from a second cleaning using my regimen. YMMV, of course.

Dougdeacon, 5-10% is a lot, especially if they are your favourite records.

Agreed. That was an off-the-cuff guesstimate. Actual # is probably lower.

It is hard for the records not to get contaminated to a degree while playing, the environment is not sterile

Other than trace amounts of airborne dust, which is easily removed by de-static and dry brush, what sources of contamination are there? I de-static and brush each side immediately after it's played. It's rare for anything at all to come off the record. I also re-cleaned and re-rinsed repeatedly when first developing my regimen. The final form of the regimen (which includes 2 ultra pure water rinses) produced results that additional cleanings/rinses almost never improved upon.

And how do you know that the first cleaning was perfect unless you clean again?

I use my ears, which are well trained. I can listen to most any record (in my system) and tell you whether it needs cleaning, or not. I did so many times while developing my cleaning regimen. I've since done it while entertaining friends and their (supposedly) clean records.

What to listen for? It's not surface noise or the lack thereof, except in this unexpected sense: a totally silent record surface indicates that the record grooves are NOT perfectly clean. A perfectly clean groovewall has imperfections that are audible in a good system. Those imperfections are the first thing masked by any layer of contamination. If I hear them, the record is clean. If I don't, it isn't.

Once the last layer of contamination is removed, the record will play with the fullest possible micro-dynamics and clarity. Since we don't always know what those should be on an unfamiliar record, they're a secondary indicator, although of course they're a primary source of enjoyment (certainly more than groovewall noise, lol).

Hope that clarifies.