You might be overthinking it. As the oil level increases in the pan, so does the surface area of the pan. It gets considerably larger once the oil reaches the top of the sump in the pan. At that point it will take a lot of oil to raise it on the stick. If it gets that high, it will be coming out everywhere! Once it gets high enough to hit the crank continuously, things get bad. They mark it in "overfill" to let you know how much you should drain back out.

The best practice is to warm it up, then shut it down and check the oil immediately. If it reads low, add as much as it reads low. Start it again and shut it down. It needs to read full right after you shut it down. What ever it is after it sets for bit, and what it is while it is running, it is.