Yeah, that's the most common indeed. Makes you think 70% of Slavic population were blacksmiths ;D
could we have Slovak and Czech surnames added?

Probably, it was the most respectable profession among commoners?
Look at non-Slavic European surnames.
Smith, Smidt, Smid(s), Herrero…
The same is with Miller
Melnik, Melnikov, Melnichuk, Melnichenko, Młynarz, Młynarczyk, Mlynár, Müller.
What is with Potter that not always may be Harry? ;D
Are these amon the top Slavic surnames?