Playing aggressive versus conservative is how you shepherd limited resources.

Do you stretch for extra seats in the House/Senate by spreading your money/people thin? Or do you concentrate your effort in highly contested battlegrounds to boost your odds locally, while sacrificing possibly winnable races elsewhere?

There’s arguments for all sorts of strategies, but a lot of it comes down to where the gettable extra votes are. Some races come down to strategy. Otherwise simply aren’t changeable at that stage of the fight.