That would add complexity to the ground combat that I don't really think adds great benefit to it. There's absolutely no way your stationing enough troops on a planet that you actually need to station them on a different continent to make space. Given that, if any of the planet is comprised of jungle rifts, I'd just want to pack all my forces into there. I believe that's part of why the concept is 'dominant terrain', as opposed to literally monobiome worlds. If it has a significant jungle component, then its abstracted that planetary garrisons and defenses are focused in these defensible areas.
Any terrain past that is open to your RP needs. Just because the dominant terrain is jungle rifts, doesn't mean you can't RP the planet as also having verdant, green plains, prime for sowing crops.