Good Point.
Quote
I am not feeding just this crop but every crop thereafter.

Plant analysis should be part of an ongoing program. 
It may help in a rescue mission.
The idea is not to Need to Rescue.  

My idea is to use plant analysis  to help evaluate my fertility program up to that p;point.
I also use the p;plant analysis to adjust my best guess for the next crop. 

A DR  Dale Pennington,now long retired from TAMU's Soils Lab advised us to use tissue and soil sampling to make our guess as to the desired fertilizer program.  .
He liked to advise farmers to know their own soil and make their own fertility decisions. 
Soil Life's suggestions fit very will with Dale's methods. .

It is a fact that, what works so well HERE my not be appropriate for  THERE.