NASA did so many studies where they tried to put together Space Shuttle parts to make ‘low cost’ rockets (saving development expenses) but whatever they came up with was terribly expensive since those parts were expensive and that didn’t matter if it was a rocket with a cluster of 4 SSMEs or a rocket that strapped on 3 of the solid rocker booster.

You’d think NASA would have read their own studies and given up rather than proceed on the predictable Artemis boondoggle.