Definition of "mass production"

After the war, the invaluable experience gained with mass production of the TP engines saw Davey Paxman in a favourable position to supply such units almost "off the shelf", a facility found to be of great value by oil companies engaged in well-drilling; [...].

1964 May, R. K. Evans, “The Ventura—Paxman's high-speed engine”, in Modern Railways, page 328

They were ruled out as over-engineered and too expensive for mass production, and lost out to Class 141 and '142' railbuses, and then Class 150s.

2023 April 5, “£35,000 needed to save a Class 317 and create rebuilt '210' DMU”, in RAIL, number 980, page 8