Low 4x4 gear gives more torque.
High4x4 gives less torque.
At angles u need low as u need raw power.
In mud u need high bcs u have less traction.
Some places u need more momemtum with the right choice of gear. As sometimes u have power but traction is low which can be overcome with a bit more momemtum. At that time a little speed with high 4x4 can do stuff which low 4x4 can't do. Never break on slopes always go down in a low gear that way no chances of slips.
Offroading is all about knowing ur gears and wat speed that gear gives u with how much power.
So dont be afraid to experiment at some safe track, once u are friends with ur mog u can always test it to it's limits. It takes time and plenty of hours of driving. I remember first track i did with TLC was shit scared. Now we are friends and i am fully aware of its capability. Dont rush in to it just give it time. And you will love this beast.