Don't know about an on/off switch, but there is a slow feathering gene K. It is also a sexlink gene and most RIRs have it too. In barreds it will clear any smuttiness between the black and white bars making a very clean separation of colors and of course, the bird will feather very slowly. That's pretty much all it does. I also believe the slow feather gene destroys type over time, especially the tails.
10 or more years ago a had a line that feathered quickly and still had pretty darn good barring, just not fantastic. As far as the utility breed that jumped out of the standard, that was it. Of course like all show breeders, I put weight and a long back on the birds, lost some utility and turned it into my pullet line. Last year I combined my two lines out of necessity. Looking back, I screwed up the best line of barreds I've seen by improving it for show. Selective breeding might separate the gene pool some, don't know.
The point of the story, it is possible to have good looking barreds that feather quickly, it just has to have the right combination of genes to do so. Like most other standard rocks, those birds still took 13 months to be in there best condition but they were in full feather and form at about 7 months.
I have always understood that the barring was caused by an 'on/off' switch that turned the color production on for a time making black, then turned it off for a time, leaving white. I have been told that when combined with the slow feathering, that is what causes the crisp barring?? Any truth to that??? Sounds like you have not heard that, or discounted it as a tale told by old wives???