I have my favorite tool, my home made scraper and the experience of being able to shave a "thousands" of an inch off, or two. I don't worry if I over-turn down .005 or even .008. I just build it back up with CA, if I am going to CA the blank.
This comes with experience. By the way, HSS scrapers (as are carbide inserts) do better on hard wood and stabilized wood but if you have soft wood, skews do better. If you are doing segments, sandpaper/abranet will work but cleaning up can be a pain. With segments, the tools do a better job of making clean cuts/scrapes than sandpaper does.
Until you develop this ability, use sandpaper (or abranet) as others have mentioned, and light touches. And as JT said, use a good quality caliper.