Has your failure to read all of the rules carefully ever left you devastated when you later found out what you overlooked? ~

Yes, all the time! I have ADHD, I am impulsive, eager, keen and excitable - so I tend to read something fast, read what I want to believe or just misread - and then go off on that basis. I frequently make mistakes that way. 

I wasn't completely devastated but pretty upset with myself.

There is a music piece I've loved to play ever since learning it.

Years went by, playing it and loving it.

And just recently I realized that all this time I've been playing it way too slowly and too loudly. And the composer, right there on the title page, expresses in very clear language how fast and how loud to play. Why I ignored his markings/ failed to notice, I don't know.

I've learned.

What a good idea --  I now play it as the composer wished. I love the piece even more.

yes, thats happened