He does wedges normally, but:
You use a wedge when:
- The razor tang is tapered like in the good old days, and
- The scales can bend a little, like horn, ivory, tortoise, celluloid ….
You use a spacer when:
- the razor tang is not tapered
- The scale material won’t flex, like wood, hard bone ….
Razors with tapered tangs and wedges are the most elegant ones, made by accomplished craftsmen. They look better, feel better in hand, are lighter, and are better overall. A slab-sided tang with inflexible scales and a spacer instead of a wedge is something that you can make with less skilled labor. That’s every mainstream razor made today, Boker, Dovo, TI, many artisans and so on.