Problem about pitch? The solution called melodyne from musicians friend is perfect for the need.
When there are scales during recording, a software such as this is very useful. This is why we listen to almost perfect music pitches being recorded by artists of today because there are already tools that can correct intonation and timing errors, plus the harmonies, timing and rhythm.
Who knows maybe some singers nowadays choose not to sing live (lip sync) because all voice flaws can already be corrected.