I organize my digital photos by date and time. I rename them using the embedded timestamp. There are various tools that can quickly rename all your photos with a timestamp as prefix. ExifTool, for example.
Once the photos are renamed with a timestamp prefixed, it is very easy to group and organize them. One folder per year. Subfolders per month or for special events. Add name of the event, persons and places to the filenames or subfolders.
No. I don't think you should use USB Flash at all, except as part of daily use. For long term storage, up to a year, use a proper SSDs and/or HDDs. And check and migrate.