Is Escort Efficiency broke?

[goodcigar]

I play as big country and have many Convoy to use. I trade and do Lend Lease to friend. I notice something weird with Convoy Escort. I accident use Destroyers without any Depth Charge because I forgot to put on. But I see that still I got 100% Escort Efficiency. This confuse me.

What is Escort Efficiency do exactly? Is it determine speed of response to submarine attack?

 

[Mousetick]

Escort efficiency is determined by the total number of ships on active escort duty, relative to the number of sea regions to cover and the number of convoys to escort.

As always, you can hover your mouse over the UI to display tooltips and gather insight on the status of things. It happens that the tooltip for the convoy escort mission is pretty good at showing and explaining things:

See Wiki link 1 for more info.
See Wiki link 2 for more advice.