My partials are from bottles of powder I never got acceptable accuracy from, or for ammo/rifles I no longer load for.
I've got W748 and W760, IMR4320, IMR4064, and maybe a couple others from the days when I tried to get my M1A to shoot like my M700 VS in .223. That was the early 80's.
I've got IMR4350 I used to use for loading for the 03A4 and M1A (not good for the M1A as I learned through two cracked op rods) during the early 80's. Still have the bullets, too.
I got several jugs of shotgun powder after my dad passed away. My brother will never reload so it was just sitting on the shelf and mom said I could take it. I used up the Blue Dot (and then bought more). I used up the Herco (and then bought more). I still have the Greed Dot and the Red Dot and have used a little bit of it with plans to use the rest of it over time.
If the powder has proven to make accurate loads for me then I use it all up. I store my ammo in a combination of GI ammo cans and plastic jugs (cat treat jugs, dog treat jugs, pretzel bite or mixed nut jugs) so having an odd number of rounds in them is as easy as writing "308 rounds" on the tag for the jug.