Source: HD2 Discord
We are performing an update to our backend logic that will change the way "impact" is dealt. Impact is the "liberation" that players deal to enemy planets or defend events. It used to be that Helldivers needed to complete an operation (usually 3 missions) in order for impact to be distributed.
Now, each mission will deal impact, and completing an operation will then deal bonus impact. This is primarily done to make sure that everyone performing missions can safely say that they have contributed to keeping the galaxy safe, without the need to have the operation complete.
Hopefully this will make the system easier to understand, and the casual diver who only has time for a mission a day can still effectively help the war effort.
This is a great change since it is pretty easy to get pulled away before being able to complete a multiple mission set on harder difficulties. Early one me and my friends sometimes did easier missions so we could complete two missions in a shorter period of time instead of risking being unable to complete three missions where each took longer.
Two missions that took about 25 minutes = 50 minutes.
Three missions that took 35 minutes + 10 minute extermination = 80 minutes