@Lakshmi Narasimhan here is how Toyota guides on the use of Low Range (a bit more conservative than Mitsubishi)
Off-Road Tips
Which Gear
Most desert driving over level ground and low dunes should be in High Range.
The constant use of Low range causes vehicles to over-heat and consume excessive fuel. Low Range should only be used in specific situations when negotiating an obstacle or for self-recovery exercises. When in Low Range the engine is reviving faster, at any given speed, when compared to being in High Range. But as the speed of the vehicle is slower, the wind flow through the radiator is reduced and the cooling process is diminished.
As low 1st has such a low ratio, it is rarely used in desert driving. In most situations is not a viable choice. For self-recovery from soft sand the first option is Low 2nd with a very light throttle pedal pressure. Excessive engine power only spins the wheels and you will go down - not forward or back!
Low Range has very useful characteristics especially for controlling your vehicle on steep descents by offering excellent engine braking. This means that when you remove your foot from the accelerator, the vehicle is slowed by the engine and you do not have to use your brakes. Retardation is applied evenly to all wheels through the transmission and the weight transfers associated with foot braking do not occur.