We know X ray number is always more than actual height gaining number.
Or more than Precice' electric remote control screen number(for example my friend now 3.85cm in erc while Xray showed5.1cm actual height gain is about 4.4cm)

So if the safe limit is measured by Xray(not every doctor use internal but every doctor take xray).
The (Ture) safe limit should be down.
We also know many Precice nail veteran have a very good result in 5-7cm.
But if the 7cm is Xray length, it would be 6.5cm in actual height and6cm in ERC.
So in this situation the safe limit would be 6.5cm.

How do you think about this?