I personally don't even have a fret rocker anymore. It disappeared and I never replaced it. I give every neck a full fret level and crown. Of course, I'm not a tech, and I really never go near high end guitars, that should already have great frets and may just need some spot work. I'm either making a new neck, buying a new neck, or dealing with cheaper, or rescued misfit guitars. I already know they've never been leveled. It's obvious, when the fret ends have never been dressed before. Some of them need the leveling more than others, but they all benefit in some degree to a full level. My longer beam works just fine for adding fall away to the end too.
I would expect, an older and well played guitar to have probably been leveled at some point. I'd assume stuff from high end and custom builders to have been leveled. Anything from a big factory though, I'd assume to need leveling. That's basically anything $2K and below. Warmoth or Allparts type replacement necks benefit from a leveling too. Have you seen the Rick & Morty bit about Morty experiencing "true level"?
Leveled frets might even be the single best investment you can make to improve an instrument.
If you can do it yourself, even better.
