Going to sound facetious for a second: whatever size works for you and the space.
It's more just what works for the space and flow. For instance, I have identical milkcrate size boxes at the bottom and top of the stairs. Why? So I can exchange them interchangably and they are easy to drop stuff into as I pass. I take the bottom of the stairs upstairs to sort and I take the top of the stairs downstairs then just toss the bin back to the closest spot so I don't have to climb stairs... lowest energy possible.
In another case, I have a small-ish tub for assorted wires. The workflow is I have a big box of wires that are sorted into baggies, I pull a wire out, I use it, I put it in the small bin, then I sort the small bin back into baggies in one go. It fits on my shelf and the intention was to prevent it from becoming unsorted wires... which it unfortunately has because I can't keep it up.
So really, it's just whatever works best for the situation, area, what it will contain, etc so you just have to find what works best for your situation.
It's more just what works for the space and flow. For instance, I have identical milkcrate size boxes at the bottom and top of the stairs. Why? So I can exchange them interchangably and they are easy to drop stuff into as I pass. I take the bottom of the stairs upstairs to sort and I take the top of the stairs downstairs then just toss the bin back to the closest spot so I don't have to climb stairs... lowest energy possible.
In another case, I have a small-ish tub for assorted wires. The workflow is I have a big box of wires that are sorted into baggies, I pull a wire out, I use it, I put it in the small bin, then I sort the small bin back into baggies in one go. It fits on my shelf and the intention was to prevent it from becoming unsorted wires... which it unfortunately has because I can't keep it up.
So really, it's just whatever works best for the situation, area, what it will contain, etc so you just have to find what works best for your situation.