It is a valid option to explore by trial and error. But once you have obtained something that seems to work, if you can't explain why it is working, it is a bad

It is a valid option to explore by trial and error. But once you have obtained something that seems to work, if you can't explain why it is working, it is a bad moment to stop. If you construct an entire system by trial and error without an understanding of how and why it's working, you are exposing yourself and your customer to serious risks. Even if things do not crash, if your code gets audited (e.g: when another person joins your team), you will have a bad time explaining your choices. As a professional engineer, it is expected of you to know what you are doing, and fudging code is the easiest way of getting sacked to the sound of a trumpet.