[Fyron]

Originally posted by Imperator Fyron:
WPs are actually hit in random order. However, each shot hits a new random WP. The damage all builds up as one sum and adds to each new shot until enough is done to destroy the WP that was randomly selected. WPs with fewer HPs tend to be destroyed before those with more HPs because the chance of enough damage having been accumulated to destroy one is greater than against a tougher WP. But, there is no gaurantee.

This is the way in which all planetary cargo is destroyed. One of the recent patches made it so that WPs get destroyed before all other cargo, but the method of destruction remains the same.