As a very new Group A / SEP class pilot, having learned on a C152 I bought a share in a PA28. An instructor on the syndicate taught me to use an approach speed of 75-80kts. The POH was nowhere in evidence, and I was still trying to get hold of a copy when I took it into an shortish (but should have been okay) grass runway airfield that turned out to have unpublished obstructions under the approach.
I approached at 75-80 as instructed, floated halfway down it, and wiped the gear off in a ditch near the end. The syndicate leader who turned up with the insurer handed him the POH with a smirk and comment "We keep it locked away so that nobody can mess it up".
Plenty wrong in my airmanship that flight (I have massively more hours and several more licences now, so hopefully some additional wisdom), but had I actually known that the book says 63kts at MTOW, reducing with weight, that aeroplane wouldn't have spent 6 months being rebuilt.
Some years later I found myself acting as an expert witness in court - I showed that a Rans S6 "manual" (almost laughable applying that term) gave an approach speed just a couple of mph above the stall speed - totally inappropriately - it should have been much faster, and also contained no warning about the aeroplane's large pitch up with power. And that was the reason somebody who had just bought one, approached at the book speed (he knew no better), then pitched up into an incipient spin when somebody taxied onto a runway right in front of him, causing a crash that hospitalised him, his son in the passenger seat, and the occupant of a caravan parked just off the side of the runway that he crashed into.
I am absolutely with DAR here - and certainly as a "grown up" have both ensured any POH I was responsible for was complete and checked, but that any aeroplane I was due to fly I had fully digested and was using the approved manual for the aeroplane.
G