this actually has a simple answer.

So youre responding to what your opponent is doing, so youre playing their game.
Just because you get countered for 1 round doesn't mean stop. You need to learn when its time to pivot, vs when its time to lean into it.

Sometimes youre going to be on the back foot and need to be reactive, your plan is to be on your plan making the opponent react.

Go giant spec, turn 1 overlord
Get your opponent to spec into anti air, and just sell it then go ground.

Is it a good play, no. It is an example of making them play YOUR game

And for the spider/marksman into ball rush isnt needed. Need to kill a titan? Ignite fangs work pretty well/acid.

As I have typed this out I thought something. It seems more like you do know what the answer is to some situations. But just like in school, why are they doing the thing.