yeah it can be tricky because sometimes it won't explode! it depends on the signal. (that part in the manual where they do it in audacity)
you should always clear any global a-rate that you mix signals into like that. but i see you've discovered the wonder of not playing by the rules! it's so fun to plug things where they will make a mess (mix some of the output of a reverb back into its input) which is why i use clip as kind of a safety net (clipping anything that goes louder than 0db just to be safe)

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