Quite so... and I suspect that English is not the OP's first language, either, so some additional consideration is in order I think.... The OP is obviously keen to learn and that's to be applauded, but I wonder if perhaps it might be better to focus on the foundations before worrying about the decorations.
Taking an amusing tangent since Tomás (kind of) mentioned stereo imaging anomalies...
I was just listening to a Johnny Dankworth Album of film and TV themes from the 60s and 70s. There's a track on it called Willie's Flat
which starts off noticeably left-heavy and very narrow with jazz piano, drums and bass all panned well left amidst 60s stereo plate reverb.
After eight bars a muted trumpet comes in with a wind section backing it, and immediately pans very audibly right across the sound stage towards the right hand side, taking the piano, drums and bass with it!
After a verse and chorus everybody in the band then goes wandering back to the left again ready for a sax solo... and when the blower has run out of puff they all go back across to the right for another trumpet section again. As the piece comes to an end everyone finally creeps nervously back to the middle for the closing chords!
It's quite hilarious... I've put a copy on Soundcloud as a private link for educational purposes: https://soundcloud.com/hugh-robjohns-443206878/1-16-willies-flat/s-lUlAAENDpd6
I presume it was originally mixed in mono, and then someone in a suit decided they needed a stereo version. So a frustrated remix engineer, probably wearing a brown dust coat and with a ciggy hanging from his lips, decided to run it through a stereo reverb and mess about with the pan-pot.
Sadly, he mistimed his opening pan for the first trumpet entry, but couldn't be bothered to do a corrective retake!