This is why I rate live performer above than recording studios performer.Recently one old video got viral where Arijit Sing was singing "Nadaan Parinde.." song and could not able to catch the perfect pitch to start with. Hence, his voice went Discordant. And he started abusing the person who fixed the microphone.
What it looked easy for us in live performance, it not that easy in real sense. A performer when singing in recording studio, gets numbers of time retake. Sometime to record one song it takes more than a day. There are so much liberty a singer gets in studio. However, the real talent comes when the same singer has to perform the same song in live. Here, you wont have such liberty and it all depend on your timing and to catch the perfect pitch or Sur. If the performer could not able to start properly, he may never performed the best.
It is always better for a singer not to start at first, let the accompaniments musician provide him the real pitch. Once the starting is done well, the entire song one can sing smoothly.
I have worked in recording studios and worked under live performance, I too myself done performance at stage and closely watched the great singer how they perform. I know completing one song perfectly is not less than a big achievement.