I think that the ideal number will be different due to octane, ethynol content, compression, and another factor that I found this year is vacuum advance.
Due to my car running on E10, vacuum advance and 9.7 compression, my current A/F is 13.8 to 14.2 cruise and WOT is 12.5-12.7. Last year w/o vacuum advance, I was able to run 14.8-15.2.