I won't allow marking wheels of any sort in my (18thc.) shop either--if you can't sew/stitch/peg a set number per inch by eye, you need to practice more IMO
Now that's hard core!! And really "old school!"
I guess I need more practice...

...although there's something to be said for the precise, almost mathematical regularity of evenly (dare I say "perfectly" ), spaced geometric shapes such as diamonds.
Of course, the eye (or at least the untutored eye) will overlook small irregularities--minute discrepancies of spacing--but somewhere down in the Stygian depths of the human psyche, such trivial deviations
are noticed and it is my personal and humble opinion that a certain dis-ease is induced which is not easily shaken or dismissed. At a level we can't put our finger on, when order is expected and not closely achieved, our regard for an object is diminished...even if only ever-so-slightly.
Which is why, being subject to all the frailties of old age...and the human condition, I rely on a 19th century peg wheel to set my pegs equidistance apart. I sure wish I could do it by eye. But if the results won't satisfy me, it ain't worth doing.
Tight Stitches
DWFII--Member HCC