In my experience, even one followup is risky after a California No, your specific wording doubly so (I've received "why don't you take the hint" to a single, very similar, followup the next day). I no longer follow up and tend to follow a policy of never asking for business or personal asks over text-based media, because a California No is harder to pull off in person. It evolves in person, though, to a "yeah, that would be fun, let's do it sometime" (and the examples in the article) to buy time until the California No can be successfully executed. I did mention the physical harm and am aware there are a growing number of folks who react violently and offensively to being rebuffed by internalizing it and taking it personally -- I know this because I've had to make conscious efforts to not tie rejection to my self-worth (I've been guilty in the past), and I've repeatedly seen rejections turn very, very ugly. So I am sympathetic that folks are often trained to -j DROP instead of -j REJECT.

Also, the situations are strongly related. It's a general theme of being unable or unwilling to say no, whether in business or personal relationships. It transfers the ambiguity of the situation to the asker: are they saying no? Did they lose their phone? Did the e-mail go to spam? Did the investor's mom die? Am I being too persistent by following up? This must be balanced against feeling entitled to a response, though, because nobody owes you anything. It's a fine line.

My personality type strongly prefers closure, and open issues like this nag me incessantly through no control of my own. I literally lose sleep over California No, trying to think of the explanation, whether business or personal. I cannot control that despite much effort. Was it something I said? Then I replay the entire conversation in my head. Then it's 4AM. The next generation is already learning that it's normal, and those of us who like (nay, need) "no" are now the diminishing minority.