Skipping Magento setup might result in conflict during runtime because Magento config will not be updated with a new port config.
This option can be used only if you 100% sure that the ports configuration is the same.
In a nutshell, this option enables start command will just restart services and PHP-FPM, so if you need to restart the project it can be done in under 10 seconds*.
* Tested on Ryzen 9 3900x system with NVME SSD with a result in 9.5s.
Sometimes, on macOS when dynamic dependencies are updated, PHP might break.
To fix this issue you need to manually delete the PHP binary in ~/.phpbrew/php/php-<version>, so CMA will detect it and compile it.
Now, you just need to pass this option in the start command and CMA will take care of everything.