<rant> I wish infosec tutorials/articles pushed writing custom tools. I've always considered password spraying to really be just taking super common passwords and flipping them around a bit. <season><year><special char> or <month><year><special char>. Instead of pushing some existing tools, I wish this article encouraged writing custom wordlist generators using common knowledge/sense. </rant>
If there is a tool/script/exploit/etc out there doing most of what I want, you can be sure that I'm going to use it and modify it to my needs instead of writing my own.
I'd say that's usually the case in 80% of the cases when doing pentests. Besides, time is money.
You could easily make such with a few UNIX tools such as date and seq plus a few variables in your favorite language. So that is covered in Linux, Bash, and Python courses.
Burp also has support to prepend or append characters. They could've covered that as it is rather powerful. They could've also covered grabbing pastes from dark web to use as input.