I just tried the "Group by" feature of Windows 10 (which I don't usually use) on a collection of about 700 photos. When I chose "Group by Date Taken" I got essentially the same results as you. Last month (8), Earlier this year (22), A long time ago (356), and Unspecified (329). But when I chose "Group by Date Created", there was a slight improvement:
- Last week (3)
- Earlier this month (2)
- Last month (9)
- Earlier this year (38)
- A long time ago (663)
I am sure your consternation lies mostly with that last group because it contains almost 93% of the images. I would typically deal with that by making sure that the list is SORTED BY Date Created as well as GROUPED BY Date Created (the SORT BY button is immediately to the left of the GROUP BY button). This ensures that within each GROUP, every photo is precisely sorted in order of age (with the newest ones first). In fact I usually just use the SORT BY feature; I do not typically use the GROUP BY feature.
With File Explorer set to "Details View", it is now very easy to do things like "find every image from the week of my birthday in 2016". There were eight of them, and they appear consecutively in the list (see the attached snapshot).
You can of course use Date Taken instead of Date Created if you prefer, but half of my images were downloaded from the web and don't have a "Date Taken" field.
If that isn't satisfactory, you could also do this:
Scroll down to the end of "A long time ago". My oldest photo is from 2013. So create a folder called 2013. Select all the 2013 photos by clicking on the very last (the oldest) photo in the list, and then Shift-Click-ing on the newest of the 2013 photos. Drag that selection into the 2013 folder to move them there. Repeat that process for each subsequent year from 2014 to 2018.