Originally Posted by YoshiEnVerde

You can't acces bonus stage if you haven't completed all current stages, which clock out at 10 sta/spin.
GHQ is twice the value of BA, putting it at twice the max amount of sta needed for normal exploration.

It actually takes the same amount of time, or complexity, to change any of those: probability or cost. They are a couple of values inside a database.
You're missing the point: You aren't supposed to finish the missions easily.
And decreasing the costs would defeat the purpose of those stages. Why stay like an idiot at any stage, say Stage 5-2, instead of advancing, if later on GHQ will cost less and give you even better rewards?

GHQ and BA aren't there to make your life easier. They're there so that you can complete some missed card, or keep spending stamina while you have no stages left. Their purpose isn't to be the most efficient, but to give you an extra feature at premium cost. Deal with it.

It sure is nice to see that there are some people who still understand logic, seriously whats the point of playing a game if everything was already given to you = Boring.