[robszumski]

This also exposes the shrewdness in using a rocket with 9 or 27 of your engines, instead of 2 or 3, which allows you to keep a continuous pace with a smaller sized production line vs having to stand it up and down.

This is all aside from the reliability/engine out gains.

[marsokod]

Yup, a mistake done in the 80s with Ariane 5 architecture, that we are still paying. Smaller scale means slower changes and this is being partially addressed with Ariane 6 and Vega C.

Similar issue with the use of solid propulsion, mainly used to also keep it in line with military needs.