I've noticed that sometimes some missions are automatically completed. If I don't mistake all these missions were about capturing and rescuing. Also - are your weapons more powerful in single missions than in campaign or it's just my imagination?
I also think that space in helicopters for men should be reduced by two (2 instead of 4, 8 instead of 10, etc.) but briefings should be more clear about how many people you should pick up in the following mission. At the same time repair resource and fuel on base should probably be increased.