Everyday is a school day. Nursing is big on what the Nursing and Midwifery Council (the governing body) call Continuous Professional Development which is career-long learning. You need to evidence CPD as part of the re-registration process to continue practicing.
I've lost count of the amount of things - treatments, procedures, guidelines etc that I've heard nurses/doctors/psychologists mention that I'd not a clue about and had to look up. Such moments I have begun to think of as learning opportunities rather than thinking "oh f**k I really do know f**k all".
Yeah I find talking about it helpful as well. A lot of the time it helps me to realise how irrational I am being.
At least worrying about whether I'm actually any good at what I'm doing shows that I care about what I do, and the effect that it has on the people I'm looking after.