And it's not like consoles are always going to work perfectly anyway. Back in the early 1990s and before, channel leakage is something that you had to watch out for, and it wasn't "NO leakage" back then, but "manageable leakage". I recall reviewing a Studiomaster Diamond 163 back in 1997 that had some very obvious leakage on high-level signals, and that was the sole flaw...otherwise, it was a killer little live desk.
-- Lugia
and even when recording bands in high end studios - there was always leakage on the microphones...
it's not the end of the world - & that's just what's supposed to be on the tape - there are many famous songs where there's an aeroplane flying over or a car driving by... big deal...
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities