That's not true. The bikes are Riv designed. Work with them on a custom sometime and you will see. You get about 20 emails and numerous phone calls planning the thing out. In fact, if you buy a production bike and have them build it you get about 5 calls and several emails deciding on parts, wheels, set up, and even bar tape color.
He has custom and non custom bikes, the non custom bikes he does not plan he requests certain specs for the price point. My understanding was that once he started sending his models below Rivendell to Waterford he no longer design the bike, I could be wrong, but that's what I heard, and that the Atlantis is essentially a 22 Series Artisan. The Rivendell made by
Mark Nobilette is more about custom request by Grant (with the dimensions of the person requesting the bike to be built) and input from Mark, my understanding was, again I could be wrong, Grant specifies which tubes to use where (he mixes and matches tubes depending on the buyers needs) and Mark does the dimension planning and build.
I think this blog sort of hints at what I think is correct:
Why buy a Rivendell or Rene Herse bicycle? | Bohemian Bicycles Blogorama