On Friday, October 21, 2016 at 11:26:02 AM UTC+3, Tango Whisky wrote:
Assuming they simply started this construction technique at some point in time, and didn't start-stop-start it, you don't have to open EVERY wing.

If the wing of SN #N is opened for any reason and found to be ok, then you can assume that all lower SNs are ok too. Conversely, if it's not ok, then you can assume that all higher SNs are bad too.

No, you can't. If for some reason (end of shift, lunch break,...)there was more time between the epoxy filling and the lay-up of the spar cap, there wouldn't be any ondulations.
The only valid assumption is that all S/N's are affected.

Even given what you say, if you find a bad one then all later ones are at least suspect.