I think Stewart Robson described it best in his interview when he wanted checkers across his arm, chest, etc. and ended up with Steve Byrne iirc. Although it probably wasnt the style of tattooing Steve might have preferred or even wanted to do, he still gave a shit, applied himself to the best of his abilities, stood back, eyed it up, looked at composition, rhythm, flow until he was happy with it and then did it.
Whether the tattoo/artist is straight up and simple "you pick em, I stick em" style or its a big custom piece, or adding to a blank spot on the arm that has previous work, a genuine tattooer will look at all the variables and fine tune it to the point where they are happy with where it is, how it sits, how its works with other work, etc.
paprika got a reaction from Ducky15568 in How to tell if an Artist is Genuine?