One for hardware engineering might be not considering the PCB itself. At higher voltages your double-sided FR-4 will become a capacitor, and at 100Mhz+ speeds y

One for hardware engineering might be not considering the PCB itself. At higher voltages your double-sided FR-4 will become a capacitor, and at 100Mhz+ speeds you'll have EMI problems from 90-degree traces. It's easy to think that you can go from a perfboard and wires proof-of-concept to a PCB in a day, but once you hit higher than ~12V or 100Mhz it starts to feel like it's haunted.