Music legends especially so. Fail to tune into the character, the voice, the instrument skills and your career could be yesterday's grits.
So when the legend to be biographed in a new stage play is country and western icon Hank Williams, you can understand why an actor offered the role would be excited - and trepidatious.
Yet Sean Biggerstaff, once of Harry Potter fame, seems to embrace the idea of playing Hank in the way a good old boy would embrace a bottle of Lone Star and a curly-haired gal wearing gingham.
"It is a challenge, but one I'm really looking forward to," says Biggerstaff, who is starring in the Oran Mor production Lovesick Blues, written by David Baillie and directed by Dave Anderson.
"Williams was, according to reports, a total maniac, a real Jekyll and Hyde character who would drink anything, including rubbing alcohol. He pulled guns on people. It's fair to say he had problems."
William's life offers enough dramatic narrative to create the lyrics of an entire country album. Growing up in dirt poor Alabama, young Hiram Williams was born with a form of spina bifida, his father suffered a stroke and the family's first house burned down and all possessions were lost. His mother was said to have bought her son his first guitar with money she made from selling peanuts. The peanut deal paid off when teenage Hiram met Rufus 'Tee-Tot' Payne, a street performer, who gave Williams guitar lessons in exchange for meals prepared by the youngster's mother. Aged 14, the hugely talented Hiram attracted radio station interest, and his career took off.
But so, too, did his black rages and his dependence on alcohol and pills, said to be related to back pain resulting from his spina bifida. Tragically, Williams' heart gave out when he was just 29, but by then he'd already had eleven Billboard Number Ones.
"Hank lived the first two acts of how the classic country and western story is supposed to go," says Biggerstaff. "He should have died overweight at the age of 50 having lost everything, but he didn't get the chance."
How to play such a conflicted -but talented - character?
"I don't know yet," says Biggerstaff during rehearsals. "It will come. But musically, country and western isn't that hard to play, and Hank seems to have a similar range to me. It's just a question of playing with the band, again and again, to get it right."
The Alabama accent holds no fears. "I rarely perform in my own accent," he says.
Biggerstaff has shown incredible performance skills since the age of 10 when he appeared in Michael Boyd's Iain Glen-starring Macbeth at Glasgow's Tron Theatre. At 13, he appeared in The Winter Guest, directed by Alan Rickman, who recommended the youngster to a London agent. But it was the role of Oliver Wood in the Potters which brought with it the premieres and screaming fans.
Did Biggerstaff's head go a little Hank? "I had been in the business for 10 years, so it kept it in perspective," he says, smiling. "How often do you see the story of someone achieving success so quickly - and then their life becoming a car crash? And remember, I wasn't one of the key players, or I may have lost it a little. Plus, I got to look at people like Daniel Radcliffe and realise just how normal he remained."
What seems to define Biggerstaff is the roles he's chosen. While ambitious, he's also clever and considered. He's never leapt into work in the hope it will bring fame and fortune, which is why he agrees to small theatre roles as in last year's production Solid Air, playing guitar legend John Martyn.
"I worked on Martyn's guitar style for a few months," he says. "That was a real challenge, walking on stage knowing I had to convince as Martyn. Now I have to convince as Hank Williams, and I'm getting the chance thanks to the fact David MacLennan (the late Oran Mor producer) who saw me perform blues in a Glasgow pub with my band.
"I never got the chance to thank him for recommending me for the part."
Yet he can repay the trust with a performance. "I'm doing my best," he says of the theatre piece, and I'm enjoying it because for me, career is all about good work. There's nothing worse than walking on a stage to do something that's not worthwhile."
Twenty songs to learn and heaps of tragedy to play . . .
"And the music was fantastic," says the actor, just two years older than Williams was when he died. "When you do a play like this you have to remember it's the reason why most people will turn out."
Lovesick Blues: The Hank Williams Story, Oran Mor, Glasgow, today to August 2 and August 7-9.