I feel like it doesn't matter too much. You can pull by aisle to keep your pulls organized and efficient, so there's no need to organize by POG in the back. It just becomes disorganized once normally light areas see a massive influx of freight. If you want to see what you have a lot of to build endcaps, use Greenfield and the Backroom Detail Report. Filter by backroom aisle(s) and sort by eaches.
The entire purpose of the backroom is to contain excess that doesn't fit on the floor. The floor has capacities to maintain presentation, but the backroom does not. So if you make the first section of an aisle dedicated to peanut butter, because that's all you need at that point in time, there's no guarantee that you won't need more than that sometime down the road. And if you fill the second section with something else, you need to either pull all of it out to keep your peanut butter sections together or throw another peanut butter section further down in the aisle.. which defeats the purpose of organizing it by section in the first place.
It's 100% better to keep the backroom flexible to help manage varying levels of backstock, especially now that everything has to be caseless. It's even easier now that we can pull by aisle, because the only efficiency to be gained is by keeping everything together while pushing.