RT is definitely important, but too much 'fiddling' with it eventually leads to confusion. Some aspects, such as climbing, require extra care though. Climb now and climb, to some pilots and ATCOs, have two completely different meanings. As said 'climb now' is an instruction to disregard the SID profile and climb to wherever.
It gets to a point where changing some RT such as 'behind' being reitirated becomes a somewhat tedious process, as an aircraft won't (one would hope!) misinterpret 'Behind the landing A320 line up and wait' as line up clearence. You can never be too sure. Better safe than sorry and in aviation there's no 'hoping' involved.
-the controller from the mountains.