Turnip Man canonically can sustain an arousal for 54 minutes. I would feel strange about typing this if it wasn't literally explained in a Marvel Comic.

THIS WEEK’S COMICS (February - July ‘76)

Uncanny X-Men (1963) #97
Warlock (1972) #11
Howard the Duck (1976) #2
Uncanny X-Men (1963) #98
Warlock (1972) #12
Howard the Duck (1976) #3
Uncanny X-Men (1963) #99
Warlock (1972) #13
Howard the Duck (1976) #4
Eternals (1976) #1

NEXT WEEK’S COMICS

Uncanny X-Men (1963) #100
Eternals (1976) #2
Howard the Duck (1976) #5
Nova (1976) #1
Eternals (1976) #3
Uncanny X-Men (1963) #101
Eternals (1976) #4
Nova (1976) #2
Howard the Duck (1976) #6
Eternals (1976) #5