I am having a little trouble parsing what you are writing. There are several threads mixed in here.
First: what the ideal strategy “should be”. I really like organizing folders by event. My top-level folders are categories like “Trips”, “Family”, etc. I can also imagine folders for events and then the top-level folders are either “Year” or “YearMonth”. In that case, I would use the start date of an even to decide which top-level folder to put the event folder in.
So, for example, if I go to Mexico for Christmas, the event will likely span something like December 20. 2019 à January 5, 2020.
So, I would have a folder named “Mexico” or “Cabo San Lucas”. I add the start date to my folder name.
So, it could look like this:
December 2019 Pictures
Cabo San Lucas Trip, December 2019
So, here is a nice thing about the calendar and events. No matter what folder structure you pick the “real folders”, at the bottom, will get buried in the tree of folders. Even if you are super organized and work hard to maintain your folders, finding the bottom folder you want can be hard. If that folder also appears as an event in the calendar somehow it’s both easy and natural. That’s a main reason I like the bottom folders to be associated with events more than just a date.
A next question is how do you get there, both on an ongoing basis, and from where you are. When I am importing from an SD card, Mylio makes it easy for me to create and name the folder at the time of import. In the case of the camera roll, I have to move sets of pictures to the right folders and it is kind of tedious.
Migrating your existing folder structure, if you want to end up here is more work. Here is another nice thing: if you rename a folder, particularly if you do the rename in Mylio, Mylio still keeps up with the pictures. Same with moving a folder. So, you can work on your folder structure and everything will keep working while you do so.
Does this make sense?