Way back, ‘
Reevaluation of 737 Safety Procedures’,
at # 2, ‘
There is no difference between the NG and the MAX in manual trim,….’
Technically - mechanically the trim system could be identical, but the installation and use, redefined by aircraft characteristics, new variants, could result in small changes which in specific circumstances are critical in safe operation.
As discussed in this thread, these changes may not be clear cut and have evolved through each generation of aircraft development. Also
737 Stuck Manual Trim Technique for some of the changes.
A key issue in safety is learning. Revisiting previous beliefs and assumptions after an accident is an important safety process - safety involves what is done opposed to a stagnant what we have.
A difficulty in reassessment is in identifying what the original beliefs and assumptions were, especially in design and certification as they may not be overtly recorded, being the conclusions of judgements about human - system interaction and human performance.