Since I stay on top of possible hardware errors using utilities, I don't want to allow my Mac to boot up and go through the checks each time. How do I skip over this process each time the computer boots by using Terminal commands, and then how do I reinstate the default startup routines if I want to have a traditional boot?
There is no official way to disable hardware checks when your Mac boots up.
These hardware tests are collectively referred to as the Power On Self-Test (POST) stage. These checks are considered critical to safely and securely booting the operating system.
You can learn more about the available boot time options through the links below: