Mostly sleep doctors are trying to get those beds filled and the cash flow coming. You will have to do study on your own to understand sleep apnea.
For example, I was given a pressure of 6 cm-H2O, then 8 cm-H2O. First doctor gave me a "brick" with no real data recording. 2nd doctor didn't make any recommendation for a better machine. With the 3rd doctor I insisted on a data recording machine.
I also insisted on an oximeter. I found out that with 8 cm-H2O my SpO2 was not very good. Periods where I dropped below 90C%. Increased weekly until I reached 15 cm-H2O and my SpO2 stopped having low points and also the typical SpO2 rose significantly.
I did this testing on my own. Also with an oximeter I found that often when the SpO2 was dropping the machine didn't report an Apnea incident and when there was an Apnea incident I didn't see any drop in SpO2. My rate now though is very low from 0 to 2 an evening. My rate is typically 0.0 to 0.2. So it could be that I am at a such a low rate that false positives are all that are reported.
I achieved a low apnea incident rate on my own. I solved my SpO2 on my own.
I am a chemical engineer and I read technical papers and so reading the medical papers wasn't that difficult. I think for others it might be.
One important thing that came very apparent to me was that the practice of sleep medicine is shoddy and of poor quality. So you need to take ownership of it yourself.