Is being "busy" a good excuse for not texting back?

It's a convenient excuse. Everyone uses it. I get it. However, realistically, how long does it actually to take to TYPE a text message? Between reading a message, and replying, we're looking at maybe what, 15-20 seconds? So when people finally reply after sometimes days of no response, is "I've been busy" code for I just don't wanna talk to you? For some reason being left on open or read is so frustrating, just take 5 seconds to say hey I'm doing x y z at the moment I'll message you later. Anyone disagree?

Is being "busy" a good excuse for not texting back?
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