For long hwy treks, you want higher pressure.

Off road, unless the terrain is soft/you need more traction...street pressure is fine. (A bit rougher ride, but you will have enough traction/flotation most of the time.

You could easily do dirt and gravel roads at street pressure...for sand or mud, or other surface where you'd need as large a foot print as possible, you'd air down.

If you need to air down, air up again to go back on road....that's pretty much it.

When you air down for off road, those tires should be fine off road at 18-22 psi or so, so to get back up to 36 psi or so for street work, you only need to air up about 12-18 psi.

If you run on road at speed with too low a pressure, it kills the tires, and makes the handling really sloppy/dangerous in an emergency.

Enjoy!

(PS - this is why I did the OBA - 30-60 seconds a tire, done.)