How do custom sliders in MyPlayer work?

I've had doubts about it for a long time. Does that trick with T-Search actually work or is it placebo effect? Also, how does it work? I mean : "User" sliders work only for MyPlayer, me, or the whole team i'm on? Or is there some kind of other way that the sliders work?

Thanks in advance

I play with customised sliders in MyPlayer mode, and I can assure you it's no "Placebo Effect". I don't know how it does work, but I play with regular sliders (HUM vs. CPU) tweaked to my taste and tested in a regular quick game, before applying them to the MyPlayer save.

I've had great results with those, it's a hard game and I get realistic numbers.