I used to have stashes for uniques, sets, rares, charms, runes etc, but I made the experience that it just makes sense to order them by purpose, as I'm browsing through my stuff by body slots and ATMA is ordering it in that manner anyway. Therefore, I ended up with 3 stashes:
#1: Crafting/cubing
#2: Leveling
#3: Stuff (including valuable socket fillers other than those for #1)
I stopped piling up things which belong into #1, it just has minimum reserves for spontaneous crafting or cubing, like when I find a good nonmagical item which needs sockets or a cheap runeword. I'm usually not keeping junk jewels or spare gems from the 3 gem recipe, as long as I don't have the matching rune for a matching, useful crafting recipe. Likeweise, I'm not keeping Spirit/Insight runes (except Amn and Tal which I upgrade to Sol [chipped amethyst needed] and Ral, respectively), as long as there's no Hel or 3 Dol + chipped emerald or even a socketable item available.
I neded more than 10 years to get rid of the worst of my packrat habits. I'm only keeping items which are useful and if they which aren't, they will have to be really rare... kind of "2 socket CoA rare". All the rest is dropped. That includes grail items. For me, picking them up, recognizing them and striking them off the list is enough. BTW, just Mang Song's and Griffon's are missing for me, so striking them off isn't needed on paper anymore