I think that the frequently mentioned "add a few knots to cover yourself" is either not understood well enough by the average student, or not explained properly by some instructors.
Twice I've been sat in the right hand seat with fellow pilots on days out and bounced down the runway quite severely on touch down. One of them damaged the nose gear strut (luckily the prop didn't strike) and one of them lead to a 20ft balloon at which point the PIC finally realised it was time to go-around. Both pilots less than 300 hours and within a year or two of completing their PPL, and otherwise very safe/competent pilots. During post-flight coffee in the club house, when talking about the two potentially dangerous scenarios, both pilots commented along the lines of "it was a bit bumpy on approach so I was carrying a bit of extra speed just to be safe".
Safe? Of course there is a valid reason to add extra speed when circumstances require, but in my opinion I don't think the subject is properly approached during the average PPL course. I also am not particularly surprised at the number of prop strikes/collapsed nose gears that we hear in the AAIB reports each month.