Nearly half of all hardware products fail EMC testing on the first attempt. Chamber time runs $1,250 per hour. A full compliance test costs $2,500 to $4,250 — and that's if everything goes right.
When it doesn't, you're looking at a board respin, a four to eight week delay, and another lab booking on top of that.
Most of those failures trace back to the same root cause: a power distribution network with anti-resonance peaks at the wrong frequencies. Peaks your processor clock harmonics land on. Peaks that show up as radiated emissions above the FCC Part 15 Class B limit. Peaks that could have been found and fixed at your desk.