That's not what it meant when I was with UTD. I had no idea what gradient factors were then. As I understood it, the original Ratio Deco started as a tweak to DecoPlanner, a Buhlmann based software. Before UTD was created, I was in a TDI program with a GUE-influenced/trained instructor. We started with a DecoPlanner schedule and then modified it according to parameters, some of which I do not recall. One of them I do recall was adding what was called the S-curve, meaning that the first deeper stops after a gas switch were longer than the subsequent shallower stops until you got much shallower and lengthened them again. This is the opposite of what most profiles do. It was done to receive the supposed benefits of the "oxygen window," a theory found in a long-since debunked paper on decompression theory.I took AG's statements about being a "tweaked" Buhlmann to mean Gradient Factors. I.e. when he talked about "pure Buhlmann" he was talking about Buhlmann with no GF used at all.
When UTD was created, my TDI instructor immediately crossed over, and all the TDI students became UTD students. We immediately dropped all the DecoPlanner tweaking and went with the UTD version of Ratio Deco exclusively for dive planning. The first deep stops were to be at 75% of our average depths, which is much deeper than most algorithms. We did the S-curve. We did not adjust for altitude because UTD does not believe altitude matters. Asked about the basis for this profile many times, Andrew answered that it is based on the way he feels after a dive. In one online session, someone asked how they could know it worked, and he said "You have to have faith!" "Faith in you?" the person asked. "Yes," he responded.
I left UTD shortly after taking part in a Ratio Deco class with Andrew. In it he admitted that the theory upon which the S-curve part of the profile was no longer considered valid, but he came up with two other reasons for keeping the S-curve. I thought both were bogus and don't remember either. At the time I left, GUE was also admitting that the theory was flawed, but as Jarrod Jablonski explained it to me, they were still keeping it because it had been successful in the past. They have since dropped it. UTD is still using it. If you look carefully at the UTD profile in post #12, you will see it starting at 21 meters.