[Babcock_Hall]

https://organicchemistrydata.org/hansreich/resources/nmr/?index=nmr_index%2F13C_shift#cdata19
When I went to the Hans Reich legacy collection and looked at a table of mono-substituted alkenes, I noticed that they used 123.3 as the base value.  I did not see methyl sulfone.  I looked up methyl vinyl sulfone, and eyeballing a Wiley spectrum, I would put the two carbons at 137.5 and 129.4 ppm, respectively.  Is this enough to establish shift corrections of +6.1, and +14.2, respectively, or do such corrections always use an average of several compounds?  I am guessing that the values in this table are based upon whatever data were available at the time, which might mean that just one compound was used.