Rule 7 of 9 · Chapter III — Package & Ship
pac pcf push is for dev loops; solutions are for everything else.
Why this rule exists
push deploys a temporary dev solution that shadows proper solution layering. It is glorious for iteration speed and quietly poisonous the moment a shared environment depends on it.
In practice
Use push freely against your own dev environment. The instant a component needs to exist in test, UAT, or anywhere a teammate works, it travels inside a real solution zip.