Were you referring to the "roller coaster" manoeuvre, where back-pressure on the control column is reduced to permit the use of the manual trim wheel to "unjam" the stabilizer at very high speeds?
To my knowledge, this certification question still hasn't been clarified, nor the reason given for eliminating the manoeuvre from the B737 FCOM after the -200.
There is little point in promoting a manoeuvre that is impossible to execute successfully
