Salute!
Some very astute posts above concerning knowledge of each A/P mode and when to use as an aid and when not to. So...
Lost a friend in the Viper who agreed with me about using the A/P to reduce workload when there was a change in plans and you needed to consult maps, change radios and IFF codes and such. Very important for single seaters. Unfortunately, he and many of us did not fully understand the "altitude" hold function of the Viper A/P. He was heavy just after takeoff and down low for entry to the low altidue nav course, then the flight aborted. Turning back over the Salt Lake he apparently engaged "altitude hold" and "heading select" to head back south. I was crossing the lake a few minutes prior and the surface was like a mirror and ceiling was maybe 2,000 - 3,000 feet AGL with scattered now showers. The snow was coming out of clouds and looking lower it was coming up from the reflected clouds. Definitely IMC. So his jet got slow and the AoA limiter stopped holding altitude and he descended quite gently at the limiter until impact, in the process of changing IFF ( we had a solid state recorder for several parameters, so hard to lie to the investigation board).
Lesson learned for all of us back then. And still valid today.