Truck and halftrack carried infantry

[Hank]

ON Foot or not

What do you do with mech and trucked infantry?

When you get near the front lines to you normally go on foot? or not?
... assuming there's a hot front line with lots of action.

... I used to rarely put my trucked infantry on foot. Now I've got to where I do it more often.
But, what benefit is there besides giving up higher movement rates?

I thought I could find the answer in the manual if there were any advantages but to no avail.