Stress and depression are two things that can impede your ability to concentrate and score the best you may have at another time. I think to know one's IQ is best for realizing one needs to compensate at times for other people's lack of similar common sense. It gives a person reason to listen to others when they talk, and to not be so critical for those who don't/can't muster up to what seem like natural expectations.

I'd play chess with you any day. I've been playing since age 8 I think, and played in summer tournaments in jr high.