The rumor is totally true. I have 3 main jackets for which I generally use temperature to dictate which jacket I ski in. It's just a general guide and I layer underneath accordingly as necessary.
I totally with tongue in cheek intentions refer to an interview I saw with Tom Brady from the Pats from last season. He said he's a machine when it comes to layering. He knows what and how many layers he needs to wear for each increment of temperature.
Since moving back to the northeast I've become a bit of a jacket, layer and general gear whore so it's all fun to me. Obviously its not as linear as just temperature because of other variables like wind, sun, etc so you take those things into account as well. However, I tell ya what I've gotten pretty good at calling it so I'm almost always comfortable. It's all fun to me but our weather here can be so wacky that my goal is always to be as comfortable as possible.
Can't wait to bring out my new Astis mittens which will likely be for 10 degree and colder days hahahaha. However if it's 10 degrees and sunny no way but more likely 10-15 degrees or colder with clouds and maybe wind.