in your guide https://randsinrepose.com/guides/apple-charging-guide.html
and in the post above, you don't seem to account for Amperage, which is a critical element in the equation and one of the key elements in choosing between 2 chargers. It is also one of the essential differences between the tiny classic iPhone brick charger and the larger iPad one. 1 amp vs 2 amps.

a good image using a pipe is here: