The last SLS launch was in November 2022. The next one is in April 2026. That is 42 months between launches.

Starship may not go 42 days before the next launch. SpaceX's Falcon 9 + Heavy has launched on average once every 12 days since 2010.

And while Starship was "in development" since 2012, that doesn't mean it was prioritized. The first prototypes were only made in 2018.