EU-OPS requires that (jet example) the operator ensures the aircraft can land on a dry runway from 50ft within 60% of the LDA. OPS 1.515
Fairytale land .. unless you pad the unfactored LDR and then figure that from the LDA. Me ? as soon as I have less than 1.67, dry, I get nervous .. and the less pad I have, the more and more nervous I get.
Keep in mind that the TP can't reproduce the unfactored AFM data every time ... the data is a tad on the optimistic side .. which is why we have the 1.67 for us ordinary folks
In the emergency/abnormal situation, I suggest that it is not a case of applying an arbitrary factor. Rather, as part of the overall planning risk assessment for the recovery, look at all the reasonably available landing options and rank them according to all and any relevant considerations .. including length. Then rank the options and make the D.