dozens and columns, differences?

[RouletteGhost]

looking at past spin data it seems to me that columns repeat in higher frequency than dozens

food for thought

[psimoes]

I have capitalized on streaking columns much more that on dozens. Ignoring columns having same chances as dozens thus we should expect identical behaviour, I'd speculate it's due to dealer signature.
Nr. 29 pertaining to third Dozen is immediately obvious. To Column B less.