I have been trying to use an Internal Motor Encoder module to find the exact distance for my autonomous code, sadly though, the distance never seems to be quite right. My theory is that each rotations is less than 360 clicks (counts). Does anyone know how many clicks are actually in each rotation?

If you are using a 393 motor, the number of ticks per revolution will be:

627.2 for torque gearing

392 for high speed gearing

261.333 for turbo gearing

What about one to one?

All of the answers above are based on internal gearing. IME only count internal gear rotation inside the motor where the red quadratic encoders (shaft encoders) count the actual rotations of a shaft. The latter is always much more accurate even if less precise (assuming torque or HS motors).

There are lots of issues with the IMEs. They tend to be susceptible to interference. Additionally, you can use a shaft encoder on a non-powered wheel and get no error caused by slippage.