Those formulas are just general guidelines, but they are not accurate for a lot of people. My max is supposed to be 194, but I've seen 196 or 197 before. I was definitely approaching my max because I was all tingly. I think I'm pretty fit, and I just work at a high heart rate compared to some of my training buddies. Usually, it just means I need to eat more often. "Resting" to me is under 168bpm. I can hold 175-185 for a long time. I don't think I hit AT until I'm at least at 187-190? My resting HR is in the 50s, but it rarely drops below 100 when I'm out and about, even when I stop the bike for a food or nature break. RHR is more of an indicator of fitness and the time it takes for your HR to drop after a hard interval (the test is what is your HR after 1 min of rest after getting it up into the upper zones, and what is it after 2 min? IIRC).

Some people are religious about training in certain zones for certain times, but I don't think you have to so much. I use HR as a guide for when to eat (and I don't eat in the upper zones usually because I might get sick), when I'm warmed up, and if I'm not working hard enough (say, in an ITT).