Vincent brings up a good point which is the basic reason for using F/stop printing. The human eye can see shifts in tonal values in approximately 1/4 stop increments. So, when doing test prints of test strips, exposing by f/stops gives a reliable and repeatable increment that corresponds with what the eye can detect.
Once you get the exposure nailed down to the nearest 1/4 stop, you can fiddle with it even more. I seldom see the need for further refinement, but sometimes there is and others will and often do.
Dodging/burning, split-grade printing, changing print size, all greatly facilitated using the F/stop exposure method.