He's counting out like 6 at a time. He needs a fast way to pick small quantities precisely, not a fast way to check large quantities. Once they're picked they're easily verified by eye.

In volume, small parts are dispensed by carefully designed machines, and then the result is counted by weight. You still need control of the dispensing, and as he's putting in small numbers of items the counting is the easy bit.

Yes it's by weight when you need exactly 20k tiny screws in a box. But when you need six that won't save you any time.

Then just use a small cup to scoop out some screws.

He needs 6 screws at a time, and the goal is to save time compared to counting manually. I'd guess that 7 would probably be fine occasionally -- maybe even 8 from time to time if the process is fast enough. I'd further guess that 9 screws is a non-starter (screws are inexpensive, but 9 represents 50% waste, which is quite a lot).

The lower limit is hard-set at 6 because the kits that he's producing and selling require exactly 6 of these screws for end-user assembly.

A small cup that would reliably scoop out at least 6 screws and no more than 7 or 8 screws sounds like a simple and elegant concept.

What does this cup look like? Is it faster to use this cup than counting by hand is? (Is it faster than the reproducible screw counter that he's already built?)

Until counting machines got ubiquitous, banks in India would count notes/bills by weight as well.

It wasn't very precise but you could move a lot of money in ball park with this method. Atleast internally across branches.

Up to roughly 100 bills it's pretty much bang on - even with a cheap $10 scale (American Weigh Scales Digital Pocket Scale has a bunch of different options). Each bill weights roughly 1 gram. So - accurate to within 1% - and presumably the banks have better scales.

I suspect at scale (moving either a lot of batches or large batches), you also need to take variance into account more. Some bills might be dirty or have stuff stuck to them, some bills might be damaged and have bits missing? And other things that occur in practice that I can't think of from the comfort of my armchair in 30s.

A scale doesn't help with dispensing the parts. You've changed a tool based process back into a fully manual process.