How short is too short for a concert?

"Cardi B carried on for only 50 minutes last summer at Target Center. The over-the-top hip-hop hitmaker might have spent more time doing her hair and makeup. ZZ Top exited the Minnesota State Fair grandstand after just 63 minutes. Does their Rock Hall of Fame career still have legs after 50 years of touring? Minneapolis music hero Alexander O’Neal performed for a mere 45 minutes at the Dakota last month. How long should a concert headline set last?" - Star Tribune is questioning as to how long a concert by a headliner should last.