Tech & Computing riddle: One of us is a promise to a customer with money attached. The other is the tighter target the team holds itself to, so the first is never in danger.

I hold nothing of my own, yet almost everything passes through me. When I run out of room I forget the oldest thing first. You only notice I exist on the day I am wrong.

I make finding fast and writing slow. I am useless when you do not know what you are looking for, and I take my fee on every single insert.

Add more of me and the work finishes sooner — until it does not. Past a certain number I spend more time coordinating than working.