Auto noise cancel often choosing less then ideal channels

With the 4500 I could swing around 360 degrees a couple times and pick a noisy bearing and auto tune. With the 7000 I point the direction I know is noisy from past experience at known locations but am finding the 7000 often chooses a channel that is less then ideal. I am impatient, but have taken the time (a number of times) to manually choose a channel and have managed to quieten down the machine substantially. I hold the machine still and scroll and listen as per directions.

(yes the 4500 often needed to be manually tuned but I seem to be doing it more with the 7000)

I might be imagining it but have also found that the machine may get noisy later in the morning (in one location) and a change of channel helps.

Are other users manually choosing channels a little or a lot, or are most of you happy with the auto tune channel selection?

Is there still a very small advantage to hearing deep signals by using low number channels as opposed to high channels?

Tributer

Initially on start-up l select ground type and gold type,
Up the sensitivity and no smoothing then do a auto tune/noise cancel
Do a JP' ground balance then adjust sensitivity and threshold until its running quiet and stable,
after about 30 min can generally up the sensitivity.

Also too high on the volume can make it sound as though the tune is out