I did some research on the net and most of it said men think about it every 7 seconds but one site said this is a myth and it happens every 2 minutes. I think every second as you put it would be excessive. There's some disorders that would manifest as hyper sexual like the manic stage of bipolar, addiction to sex, obsessive thoughts etc. If this is more than usual and it's affecting your life in a negative way, then you should consult a therapist.

This is what the website said: "According to an intense Kinsey Institute study, the average man forms a thought about sex approximately every two minutes, and that he generally ponders the thought for about a minute, 50 seconds before letting go of it.