Feet are actually great units for RF because a nanosecond is very close to a foot. Since feet has many prime factors and/or the foot-meter conversion is also easy, you can quickly get a wavelength of, say a 2GHz (6 inches), and get it in cm (15cm).

Of course, ideally we'd ditch the silly metric system and use natural units. Then these 30 feet are a more comfortable 50M/eV. But those SI guys are really conservative and attached to confusing unit system based on fractions of the diameter of an arbitrary planet.

Obligatory: https://www.xkcd.com/3248/