Really good post.
I had raspberries for the last 6 or 7 years in one spot in the garden and after they got established they did very well. I had June bearing plants on one end of the patch and everbearing on the other. I made the mistake of planting a couple of wild raspberry plants in the middle. They basically took over the patch and didn't produce very well. I dug up the patch last year, it was where the greenhouse is now. I gave away a fair amount of the everbearing plants, some to a neighbor and some to my daughter. I planted a few on the back corner of the lot. They lived through the winter and a couple of them are full of flowers now.
With your post, now I understand how the everbearing plants work.
Yes it's nice to know there's a late crop coming. My harvest have not been great with the primocanes though partly from squashing the tall canes with my row cover in the summer and then with the yellow jackets eating them in the fall. I didn't mention that in my article but that's another problem.
Last year I had problems with maggots on the inside of the berries. They looked ok when you picked them, but there would be tiny worms inside the berry. Some kind of bug larvae. It wasn't all of them, mostly just the really ripe ones on the shade side of the plants.
My son found a little worm in one the other day. Now he is sticking with the blueberries.