Things to keep is a small list.
- constantly consumed stuff: rocks, wood, meat, arrow components etc
- at least one second-best or if wealthy, duplicated armor set and weapons for corpse runs into bad areas.
- hard to get stuff, mostly refined ore, or excess chitin that would be a pain if you suddenly needed some.

what does that leave? trophies, unused or lightly used consumables (dwarf eyes, resin, skins, low tier stuff)

I am a packrat and we have near infinite storage. That said I use a 'darwin' approach to what makes it back home. Hmm, found lox meat, but have grey dwarf eyes in my bag already... toss the eyes. Hmm, killed a sea monster but have coins... toss the coins... etc.