We're to be fully out of reverse by 60 kts.
Is that the manufacturer's recommendation? Depends on aircraft type. For example B737 FCTM states: "Maintain reverse thrust as required, up to maximum, until the airspeed approaches 60 knots. At this point start reducing the reverse thrust so that the reverse thrust levers are moving down at a rate commensurate with the deceleration rate of the airplane. The thrust levers should be positioned to reverse ideal by taxi speed, then full down after the engines have decelerated to idle. Reverse thrust is reduced to idle between 60 knots and taxi speed to prevent engine exhaust re-ingestion and to reduce the risk of FOD. It also helps the pilot maintain directional control in event a reverser becomes inoperative. The PM should call out 60 knots to assist the PF in scheduling reverse thrust."
You can't get it more clearer than that.