Don't send your supply ships back to base if you can help it, takes way too long if you have really brought an entire 20-30 ship fleet out there (wherever that may be) instead just bring along a colony ship and build an advance base. Plus by the time you use up 3-4 cruisers/bcruisers of supplies you should have accomplished your mission.
The logic behind this is that if you send back your supply ships and rotate them then you will have little supplys cause they will use them all up getting there.
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