Does crafting ammunition create one piece, or a batch?

I’m looking at the rules for crafting, and I’m somewhat surprised to see the following:

You must spend 4 days at work, at which point you attempt a Crafting check. The GM determines the DC to Craft the item based on its level, rarity, and other circumstances.

So if a wizard were to craft a staff, it would take 4 days. Fair enough. But suppose the same wizard wanted to craft Spellstrike ammunition – let’s say arrows. Would it take 4 days to craft a single arrow? Or is there a rule somewhere stating that after 4 days, a quiver of, say 10, would be created?

Having it take just as long to craft a magical staff as it would take to craft a single magical arrow seems a little absurd to me – the first is a permanent item, the second is single-use.

Can anyone shed some light on this for me?