So what your saying, is that pyramiding might be caused by faster growth? Sounds like a possibility. Would have to get the input of some more experienced members...I dabble in a bit of 3D printing and one thing that comes to mind is print layer resolution. Now just bear with me, but what I am referring to is the distance between each layer in the Z axis (up and down) as the filament gets deposited. In 3D printing the higher the resolution the smaller that distance becomes, which turns out in higher quality and smoother prints. In other words each individual layer uses less plastic than a lower resolution layer, but the overall print takes much longer to complete.
As a pretty much inexperienced keeper speaking out loud what I am saying is that maybe the tortoises are experiencing "low resolution" growth due to the consistency/availability of food. Faster growth, than in the wild, could mean thicker "layers" as they "build" giving the carapace that raised appearance. Could it be that in the wild tortoises experience a sort of waxing and waning availability of foods (thinner layers) and take much longer to grow (longer print time)?
Anyways that is what came to mind.