Interesting question. I got rid of most of this stuff at the 14 month mark after retiring. I had early retired and extensively downsized almost immediately and within about 3 months of ER started what would become a 10 month long trip abroad to Southeast Asia and then South America (with a one month USA stopover in between, so 9 months spent traveling). I just went back and looked at my email from that time, and within one week of getting back from South America at the end of this journey, I had started an Amazon bookstore and basically sold almost everything in a few weeks. I think I had kept most of my college homeworks until then, also, but I threw them all away at that point. I also sold a car I had been keeping in the USA. I had decided that retirement was for me!
When I retired in 2007, the S&P was about 1450. When I sold everything in 2008, it was about 1270. Now, if I had known the S&P 500 was going to drop into the 600's in just a few months, I probably wouldn't have been so enthusiastic about getting rid of *everything*, which is what I did.
However, absolutely zero regrets now.