I am reading tons and tons of my mom's files of paperwork to prepare for our lawyer handling her eldercare affairs. Mom was darn good at being organized even with the onset of dementia which I was made aware of around mid 2018 but it appears began as early as 2013 according to at least one " doctor's orders" type page I found in her medical files.
It is the financial ones I am struggling to amass and verify that I have every month's statements as far back as Oct 2016 to present. All the while relocating all her belongings from Delaware where her apartment was, to a storage place and our home here in Maryland. Thankfully like I said, mom was pretty darn organized. Things just had a few holes and was reasonably intact despite the dementia and 4 moves in the past 10 years she was in Delaware.