"Do I need this word?" If people use it you need it. And there's only one way to find out if people use it. And that's the same way as learning how to use it. Stop caring about these questions, about some sort of false efficiency. And just consume the language.
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And technically if you really learned it from that impression alone, and it was common enough to come up again you wouldn't need the Anki card. Since sentence mining is about sustaining the level you're at, rather than studying something new.
Feels hard to pinpoint exactly what you want in an anki card then. I wonder if "seen X times" is a good way to filter it. It definitely takes stress off of Anki though. If it's for words you already have a strong impression of, not something you're seeing for the first time.