It might be worth remembering that, at least in the FAA world, the landing performance distances give no credit for thrust reversers (EASA is a little different but I don't know details).
FAA landing distances are established by landing on a dry runway with max braking and no T/R. This is done multiple times at different landing weights to establish a weight/distance baseline. Then a factor is applied - a rather large one (2.4 comes to mind but don't hold me to that) - to account for things like low friction runways and less than perfect technique.
Any improvement the T/Rs provide is considered a bonus.