My guess is that some of it has to do with nationality. Paley is in a very litigious country and orthopedic surgeons are disproportionately sued compared to other specializations.
That makes sense, I didn't think about the countries/nationalities
I think Nemer (Ukraine?) and Birkholtz (South Africa) recommend about 4cm on tibias, but 5cm seems more common with other doctors for tibias. I think Dr. Parihar (India) and Dr. Giotikas (Greece) often allow patients to go to 6 cm. And then I think Dr. Paley and Conway (USA) recommend 5cm tibias
And it seems that Guichet (Fra) and Betz( Germany) allow patients to push 7,8,9 cm+ on tibias, though I might be mistaken for Guichet
The other thing I noticed about betz is him not doing IT band release most of the time for femurs and his reasoning for this. He talked about how some patients were able to go back to work very soon after the surgery partially because he didn't do the IT band release and how he only does IT band release in some uncommon situations. I also find this a bit odd how doctors can disagree so much on this issue -- to my mind, it feels like Betz is catering more towards the best/better case scenario patients whereas other doctor with practices like 5cm tibia limits + immediate IT band release for femurs are catering more towards the worst case scenario patients
And this is making me think "if someone knows that they have bad flexibility, maybe they should default to going for the more conservative rules, ex: 6-7cm limit on femur, 5 cm limit on tibia, and do IT band release for femur)
The other issue I know doctors disagree on is whether to fix the upper portion of the fibula during tibia lengthening and Dr. Giotikas said that among surgeons around the world, they were about 50/50 split on this issue at a conference, but the reasons he explained to me flew over my head