I can not find the FAA AC I was looking for but AC 91-79 has some good advice which indicates that arriving over the threshold at the correct height Vref +10 and touching down in the correct place will add approx 300 ft unfactored to LDR.
An extended float can add 2500' then wet runway, shallow angle and being above 50' over the threshold with power still applied will all add distance and very soon your LDR can be in excess of 3000' more than you calculated. This is not good.
Remember that the AFM figures are usually calculated for 50' over the piano keys with the engines at idle on a 3 deg glideslope. In a small business jet this will have you correctly in 3 reds 1 white (see tech log PAPI thread where some grown ups have posted some good advice) and touching down at Vref -7 to 10 kts. Any thing more and you are seriously increasing your LDR.
Stick to the book speeds.