The stuff it covers is also in the NOTAM so you don't need to do both if you don't want to, however some may want to as a belt and braces answer.
It's worth doing it every time - takes out any worry of 'not seeing the NOTAM' for airspace they would nail you for. ie if you happen to miss a notam in a long list about kites over the Isle of Wight, well, who cares but you and the kite owner? If you happen to break a missed Red Arrows display area, you just put another tick in the 'why its right to make GA spend money on Mode S' list
Anyway, I'm arguing against myself now - these pilots don't read NOTAMs to be able to miss them!