Land Rovers in particular, made permanent 4WD vehicles as it does improve handling on all surfaces. Because of the very reason explained above with part time 4WD vehicles, the Land Rover Transfer Case has a differential between the front and rear drive shafts to prevent the windup.
Because of the third differential, a Land Rover will stop with any one of the 4 wheels that slips. To rectify this and to put the Land Rover in the same position as a part-time 4WD vehicle, the centre differential can be locked, therefore the differential will behave as if it was a solid shaft.
Many softroaders though, have the permanent 4WD transfer case, but without the locker and also no low range. This will obviously limit off road ability significantly.