In snapshot 4a, I was able to generate a 1-tick pulse by using two droppers. The droppers would be facing into each other. By powering 1, then powering the other 1-tick later using a repeater, The second dropper would possess an item for one tick. A comparator could then send a 1-tick pulse, which is a very useful behavior.

When transferring an item from 1 dropper then back, a comparator should have been able to send a 1-tick pulse.

In 5a, it seems that items that are deposited and removed within 1-tick are not measured by a comparator.

You can use a setup similar to the one in the attached image to duplicate this instance. The droppers must be facing each other.

Something to note; If the attached comparator is measuring the inventory of the dropper with an item already inside, before the circuit is activated, a comparator will blink off for 1-tick; the duration that the item is absent.