I think it depends on what your goal is! For example, being an interpreter, a conversationalist, or just communicating are very different. For something like being an interpreter, I would definitely learn them all– even when you think you have, ASL is like any other language in that new words/slang/accents come up. If you’re trying to get to the conversational level, maybe not all of them but it will definitely be more useful to learn different variations for the receptive part of the conversation.
As far as communication, ASL is great in that you can get your basic point across (even with fingerspelling). However, it’s always useful to learn more! And the more you sign with native signers, the more you’ll pick up.
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