Concerning the window "Recent opened" or "last viewed", I am not sure of the name since my language version is polish.
I had a file on the list, that I wanted to view again. Unfortunately it was on a share that was not connected at the moment.
Acrobat Reader could not open it, and it removed it from the list. I connected the share, but I lost the possibility to open the file since it was not on the list anymore. I had to find it again, what was really time consuming.
The file should be kept on the list until user deletes it.