They have degraded significantly over the last few years. Up to around 2015 it was about my #1 reference source. It's how I found out about the fact many GPUs used to triple or quadruple their power consumption just because of an extra monitor being connected, and that AMD's HBM-based GPUs were at that point a surprising exception (when otherwise AMDs GPUs are usually the worst at it). These days however I have to take everything they measure with a grain of salt, and at some point I even had a discussion with a member of staff on the merits of having idle power consumption measurements at all. Something has definitely changed on their side.