[ballenf]

Or to put it in other terms, you want to consume memory at a rate lower than propellant.

[elil17]

Well, for ballistic missiles a large portion of the flight will be the mid-course phase (which is typically unpowered) and the terminal phase may use control surfaces for maneuvering. For cruise missiles that's a good rule of thumb.

[Someone]

Not typically, always. “Ballistic” in “ballistic missile” means “moving under the force of gravity only”

[elil17]

Might you not use some fuel for countermeasures during the midcourse phase?

[tomatotomato37]

Yeah, a ballistic missile's bus still does a lot of horizontal maneuvering during the mid-course phase to actually get on target; the main boost phase is mainly just for getting it pointed in the general direction and proving verticality

[marcosdumay]

I imagine RAM weight is not a relevant parameter on the rocket equation.