@Judystilldreamsofhorses
This percentage rule is something I saw in a book by Anuschka Rees, The Curated Closet. However, she might have read it somewhere, too....
@Zippedydodah
As long as you have suitable space for the clothes and they are not in danger of deteriorating, I wouldn't clear out everything. There were many good ideas mentioned on this thread, but if the clothes keep, those which are simply too numerous now could still be kept at the back and you could wear them in a couple of years when the current lot is worn out.
I would also consider that you will hopefully live very long but in retirement you have a fixed amount of income and not so many earning options anymore.
Looking at the news, the prices rollercoaster and the political situation, things could become much more expensive or hard to replace when resources are not as available anymore (remember the restrictions from Covid and the problems with production when supply chains are interrrupted).
I wouldn't rely on being able to always shop and replace stuff at a whim in years to come.
If you have the space and are not moving anytime soon, I would at least keep items which are nice but still too much in amount for a different year.
The selling sounds so easy, but numerous people have problems with buyers on Vinted or Ebay (or Facebook marketplace or whereever), or the companies do not release your money for some reason, there are scammers, too, it is time consuming to make sure one has good buyers. And the prices, unless you have collectibles, are never anywhere near to buy you a replacement.
That's why I would only discard items which are either worn down or where you are really sure you don't want them anymore, like specific work wear or suits etc. That can already free a lot of space. But I wouldn't get rid of anything just out of principle.
If you don't need the sales money and have suitable clothes for the recipients, perhaps a women's shelter would be another option, as often they have to leave their home with very few things.
by the way, I read that even Marie Kondo doesn't kondo like she used to do, now that she has children and a family life. Perhaps that's one small hint that her idea isn't universally suitable for everything and everyone.