You've imagined one way to do it, but there are lots of other approaches. I prefer organizing photos using database search methods over putting them into specific Finder folders. Search means the images can be located in many different ways.
To me, Finder folders are way too rigid - what happens when you want the same photo to be found in two different folders? After all, you may want the same image in "Family" and "Favorites," right? What do you do, make an extra copy of every 5MB file? What if you then edit the image - you'll then have two different versions of the same image. Will you remember to replace/update the copy in the other folder?
You could give up on the idea of using physical folders, but instead use the Photos app (or iPhoto) to sort those images into Albums. Very fast and easy - just mass-select, drag, and drop. The same images can be put in multiple albums without using significant hard disk space, since the contents of albums are lists of links, rather than image files. If you edit the image, the updated version appears automatically in both the Family and Favorites Albums.
Instead of creating Albums, you could also use Photos' Keyword function to categorize them, and simply search on Keyword when you need to find them by that keyword. Again, you can mass-select the images and assign the same Keyword to all of them. Photos makes it easy to flag (and un-flag) images as Favorites. iPhoto makes it easy to assign star ratings... so many ways to mark/un-mark and categorize images without using additional space or shuffling them from one folder to another!
You can also create Smart Albums - these automatically populate as you categorize your images - no need to drag them anywhere. Photos' Favorites album is an example of a ready-made Smart Album, but a custom-made Smart Album can include multiple criteria, including date ranges (all Favorites of Family for May 2016, let's say).
If you'd rather not use those apps, you could also use the Tags feature of Finder. Each tag could be a different photo category. The images could be anywhere at all. After categorizing, you could view the Tag "folder" by clicking on it in the Finder sidebar. You could then do a Select All, and drag all those files to the "physical" folder of your choice. Or, just leave them where they are, and access that Tag "folder" when you need to find them based on that particular criterion.
All you have to do to take advantage of all this power (at least, I consider it power) is to abandon the notion that you have to put one image file into one folder.
Of course, plenty of people can't wrap their minds around the notion of using "virtual" search/keyword/tag-based methods, instead of a physical-seeming folder. The fact is, those folders are total illusions - there is not a physical location on a HDD set aside for the contents of a folder. There is no envelope, drawer, or box holding those files as if they were film negatives. The files are scattered all over the physical HDD - if the file is particularly large, it may even be in multiple pieces! The disk directory simply knows where to find them.
