Noooo that was my whole point is your brain doesn't fill up to the point where you can't learn anything new or the old stuff gets lost. It's not one thing at the expense of another. Sure, if you never use certain knowledge it will eventually get lost. You have to keep it fresh which is what spaced-repetition does. People have learned a lot about how the brain works and we can take advantage of it.
Here is a bird with arms.
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