Inside a game, if you click:
-Menu
-Settings
-Search Bonuses and Territories

It will show you the total number of armies earned on the map if all bonuses are held.

lol noob

Pretty useful. You really should know how much you would make if you controlled EVERY territory :)

Sarcasm aside it is pretty useful. Particularly in FFAs

After all these years I never knew that, that'll save a lot of counting in the future.

Here's how its useful... In a 1v1, if you have 50% or more than than, you should win. It's helpful to estimate the strength of the enemy by counting. Assuming you have ~40% of the map, you can quickly add up what you see in neutrals that are not complete bonuses, then your opponent has maximum Total-(Your income + Unfinished bonuses visible)