Consider how a bad weld can turn into a stress point that fails over time, not right away. That's the real issue, not how it looks today. A small crack can grow with vibration and load until something breaks when you least expect it. It's about hidden weakness, not just surface looks.
Read the_adam's comment again. He's not wrong. Saw a pipe weld on a feed line let go last year. Looked fine at a glance, but it had a cold spot. Held for months, then one Tuesday it just split. Shut down the whole line for two days. That hidden weakness he talks about is real. It's why the double-check feels slow but saves you later.