There is tracking an actual radial from a VOR and tracking a
radial inserted in the box (then NAV'd or LNAV'd).
Some radials aren't perfect and have their minor twists and
turns. Suppose one steam-driven is inbound to a beacon and
one with a FMC outbound (flight phase immaterial), and both
are given radials to maintain minimum lateral separation.
If I'm given a radial by ATC to track in or out with min sep in
the equation then I'll use it. (eg KCH VOR in Malaysia is one I
recall with a few bends in radials within the Western sector).