This is spot on. I learned this the hard way. I have been trying to get rid of an idle surge in my '90 Mustang for over a year. I finally figured out that it was going into closed loop at idle and trying to maintain a target AFR. It kept adding and pulling fuel trying to reach the target, but of course caused an idle surge. Once I realized that, I changed the closed loop settings so the engine is just running off of the base fuel map at idle. Once I did that and adjusted the base map a little bit, my car idles perfectly.Most engines maintain stoich at cruise better than idle. Idle is tricky. Check you wideband at 2000 rpm light throttle cruise.
Doesn't need to be super accurate, just consistent. You are going to check your WOT AFR then makes adjustments from there. You'll find a number your car likes and you know that will likely be different than other cars.