Let's save both you and the universe some time by never asking that question ever again. As a general rule, John Belushi was destroyed when he was on set, perhaps no more so than when filming The Blues Brothers, his and Dan Aykroyd's tribute to doughy white people truffle-shuffling their way through blues standards. Everyone involved in that production did their share of drugs, especially cocaine, which was actually worked into the film's budget. But they all saved the brain-tickling moon dust for night shoots, because what maniac would load himself up in the middle of the day on the set of a multimillion-dollar movie?

It was originally set in winter, but he kept inhaling the fake snow.
John Belushi, that's who. Belushi treated drugs like his full-time job -- the movie was incidental. It didn't help that The Blues Brothers was filmed in his native Chicago, where every junkie in town wanted to say they got their hometown hero high. As a result, Belushi would routinely disappear for hours on end. Aykroyd had to go on numerous adventures simply to locate his sky-high co-star and carry him back to work. On one occasion, Aykroyd found Belushi sleeping on a couch in a complete stranger's house at 3 o'clock in the morning. Aykroyd just kind of shook Belushi into a state of semi-consciousness and dragged him back to filming. Presumably a portion of Belushi's scenes in The Blues Brothers were actually performed by Aykroyd manipulating Belushi's drug-slumbering body like the titular corpse puppet in Weekend at Bernie's.

"I paid Jim Henson 50 grand to help me jury rig pulleys to the steering wheel."
And if Belushi couldn't find any random enablers to party with, he'd host his own Miami Vice deleted scene all by himself. On one occasion, director John Landis walked into Belushi's trailer to find his lead actor perched behind a literal mountain of cocaine. Landis had to battle Belushi for about 15 seconds before the man finally apologized and agreed to allow his stash to be flushed safely down the toilet. Belushi got so out of control that he eventually hired a bodyguard whose sole job was to prevent him from doing any more drugs while they were still filming. He was essentially the Bruce Banner of that production, requiring constant care and vigilance to prevent him from hulking out, tearing his trailer in half, and reappearing four days later on a moped in a pair of hobo pants.
