I've seen people who don't "get it"..but I've never had anyone actually admit to it.
If you are already considering taking a refresher course, do it. Read alot...not just nursing journals, read charts, read H&P's, read your state's laws. Read, Read, Read.
Next ask alot of questions. Asking the question is not "stupid"...not knowing and NOT asking is "stupid". Never assume...find out.
Over the years many of the nurses I have worked with who didn't "get it" when counseled about why they did what they did, would comment "Well I didn't know, so I thought...." Find out...don't wing it.
The last thing I can tell you is that sometimes people are just unsure of themselves by nature. I've been working as a DON since 1987...there is honestly not a day that goes by that I don't wonder if I know what I'm doing. It's my character make up. I look at the "big picture" and could about pee my pants, and then break it down into small pieces so I "can handle it"...and just do it. One day at a time, one hour at a time.
It's my nature to look at "all that I'm responsible for"...and it scares me...sometimes I go to work with sweaty hands and my stomache aching. The minute I walk into the door and break it down into the daily tasks I have planned and handling "at the moment" issues...I am fine. I guess what I'm trying to say...our fears can be paralyzing IF we let them.
Hope this helps and good luck