There are known knowns. These are things we know that we know.
There are known unknowns. That is to say, there are things that we know we don't know.
But there are also unknown unknowns. These are things we don't know we don't know.
Sometimes, it's good to listen to those folks who have persevered through all 3 stages themselves & are prepared to impart their subsequent knowledge to all, thus reducing the learning-curve heartache for the rest of us.
Did I just get a bit overly "wordy"? Sorry.....
I've been reading this thread from a couple of years back & I'm constantly making notes on stuff.