Conversion to type. Instructor-"70 knts on final". Me-"55 would be better". Instructor-"No, 70 knts, 65 over the numbers". Resulting float with help from ground effect eats up the runway to the point where a go-around is prudent. Aircraft in landing configuration stalls at 34 knots.
From the PA-28-181 POH:
"The airplane should be trimmed to an initial approach speed of about 75 KIAS with a final approach speed of 66 KIAS with flaps extended."
Unless you are
absolutely sure you know what you are doing, stick to the POH numbers.