I don't want to insult you, but in case people don't understand. 4hi does not have any additional gear reduction.. It is simply engaging the front axle.
4lo is when you need more torque. ie steep hills, bogged down by mud, or pulling someone out. Also, if you are navigating a technical section of trail and need to go slower, 4lo is a good idea.
If you decide to try to get unstuck from a mud hole in 4hi, you might not have enough low end torque to get the tires spinning, and can also risk transmission damage. Good rule of thumb, if you feel like your rig is struggling, or slipping the transmission a lot, then throw it in 4lo until you are out of whatever you are in. Since you have a rubicon, you are gonna be 4 times slower in 4lo than 4hi. ie- your top speed in 2 wheel drive might be 80- throw it in low, and now your top speed is 20.. Make sence?
Hope this helps
My ride- 2001 power wheel, 11" plastic tires, upgraded battery, boat sides, custom bumpers, tow hooks, new paint.