Why does the majority of people still use the test strip method that is the negative projected onto a sheet of paper, and the card sheet used to block it into sections?

Just looking at videos, its the most commonly done and most commonly abuse method in that people will overlook how critical detail in the boat house on the lake is perfect and crip and visible, in order to use a different time section that shows the lake slightly better, but leaves the detail a solid black..

Lambrecht with way beyond monochrome, i have seen bits and pieces of pdf files hes loaded to photrio, went with a localized test strip. Featured on the most critical component of the print. In the book he used a photo of a woman in a shaft of light inside a barn. did a test strip sheet just on the woman, found the bestest time for her, did a work print, it was almost there, made an adjustment and voila, third sheet was a good final print.

I dont understand the reasoning behind the whole image chopped into portions as a means.