In general certainly would not advocate leaving landing light on in cruise. Bulb life will reduce and the chances are one day it will go in transit leaving you struggling on landing. Power demand can be quite high with relays, switches, wiring, generators and batteries all working harder. Considerable heat is also generated which can age plastics.
Exception though is in times and areas of high traffic density, esp at funnel points such crossing airports etc when daylight use is also good.