Thoughts on optimizing gain

Today i took the free time and played around with the gain.
I switched from 49.6 back to max/agc which did not change much except the number of messages > 3dB which increased again up to 8-12% in average

Then i changed the setting to a lower value of 42.1 and let it run for a while

Except the reduced number of messages >3, signal level and the CPU usage of ADS-B nothing seem to have changed.
The number of aircraft is the same, number of tracks seen etc is all the same/similar to previous hours/days with similar traffic. The range also did not change so far

I am using as you might know already the blue FA pro plus stick with a modified indoor antenna on a can.
Does this mean the changes does not have that much impact because i am not using an “optimal” physical setup? Or is the change between max and 42.1 that low?

EDIT: Just have seen this thread. seem to be that the values of 40 and up did not change a lot on the pro plus stick.