One other tangential source for learning regex's that has/does help me is an editor like sublime(non-free)
that shows matches as you type in your regex. I have run into just a couple along the way over the years that behave
like this. Unfortunately, I don't recall them all, only sublime. Very handy when learning to be able to have instant feedback
when constructing an regex... :-)
Just a thought...
...the majority is always wrong, and always the last to know about it...
Insanity: Doing the same thing over and over again and expecting different results.