Just because you use it doesn't make it in any way 'usual'. Just because you learned it in some school doesn't make it non-regional. Also, your own example "饾懃" is decidedly not of the )( form, but of the 脳 form.
"I was taught the ")(" way at primary school" is a perfectly reasonable response to your question, which wondered whether it was just one person's preference. That answer tells you it isn't.
Nowhere did the reply suggest it wasn't regional, nor, for that matter, that "/ \" isn't regional. Both are presumably regional, but whether one is more common requires a fair bit of work to answer.