This is a really hard idea for a lot of people to grasp. I am going to say roughly the same thing in a way that may help some people understand the issue of "decompression efficiency" in different terms. I may just confuse people more, but I will give it a shot.The NEDU study proved that is better to go shallower, but if you feel doing a deep stop and then consider it an extension of dive time rather than decompression time and therefore increase you shallow decompression time you will do more decompression. This would off gas the additional inert you have on gassed staying deep longer, you might have reduced the gradient on you fast tissues early on, and compensated for the need of off gassing longer the slower tissues after the further on gassing imposed by the early stop. Obviously it would have increased the total deco time and decreased decompression efficiency.
Let's say I want to do a dive that requires X minutes at depth, and my algorithm tells me I will have to do 30 minutes of decompression at various depths. If I instead choose to do X + 5 minutes at depth, I will have to do additional decompression time. No one disputes that.
Let's say I instead do X minutes at depth and then add 5 minutes of deep stops to my ascent. Are those decompressions stops, or are they added bottom time? If I add additional shallow decompression time to compensate, then what I am really doing is considering the deep stops to be added bottom time that requires additional decompression.
But is there a benefit to adding that additional, shallower bottom time/deep stop, whether you don't add extra shallow time (as some people advocated) or do add the extra time, making the ascent less efficient? That is the big question right now. With the Buhlmann algorithm, the most efficient way to the surface is 100% Buhlmann, but no one I know one is advocating that. Most people I know are thinking that there is some benefit to starting a little deeper than 100% Buhlmann and then adding the extra shallow time. They just don't think it was a good idea to stop as deep as people were advocating before, even with the extra time shallow. There is no value to that much added time.
So everyone using Buhlman with GFs is doing deep stops to some degree, and those stops are a blend of extra bottom time and decompression time. They have to do additional shallow stop time to make up for the increased bottom time, but they hope to achieve a benefit from that added decompression time as well.