A-yep. Of course, there are some folks who spend so much time shooting all sorts of stuff all the time, they can pretty much pick up anything and hit whatever they want within effective range.
I'm working on that myself... !
The problem I had with shooting one gun almost exclusively was not that my practial accuracy with other's suffered, it was that the manipulation for things like reloading started to get hardwired. I remember shoving on the triggerguard of my Kimber to drop the mag, since I'd been shooting a Walther P99 alot and thinking "This would be really embarassing under certain circumstances."