Warning! SPOILERS for Young Sheldon season 5.
CBS' Young Sheldon retcons Sheldon's (Jim Parsons) most annoying trait to Leonard (Johnny Galecki) in The Big Bang Theory. The prequel sitcom builds on the story of its parent series, with new revelations about the socially-inept genius' childhood in Texas. However, there are also instances where Young Sheldon changes Sheldon's behavior, effectively creating plot holes for the character's overarching story.
Debuting in 2007, The Big Bang Theory initially only had five main characters - Sheldon, Leonard, Penny (Kaley Cuoco), Howard (Simon Helberg), and Raj (Kunal Nayyar). By its fourth season, recurring guests Bernadette (Melissa Rauch) and Amy (Mayim Bialik) were promoted to series regulars. Despite being an ensemble sitcom, the show's true lead was always Jim Parson's Sheldon. He was typically the center of narratives, and on the rare occasions where he wasn't, he was still an important player. Although he dated and eventually married Amy, Sheldon's most important relationship in The Bang Theory was with Leonard, since they'd been together as friends even before the show began.
Viewers had seen Leonard tolerate Sheldon's antics in The Big Bang Theory. Before Amy and Penny were even subjected to his oddities, Leonard was already dealing with him since they're roommates. Given how long they'd lived together, Leonard had experienced Sheldon at his worst, but that wasn't even the most difficult part of it. Instead, it's the smaller things that he got bugged about every day, which included being forced to adhere to a strict schedule at home. This is why it stood out when Sheldon started complaining about having to work on a schedule for his college friends in Young Sheldon season 5, episode 10 titled, "An Expensive Glitch and a Goof-Off Room." In it, he had to take in and organize requests from his fellow students to use his part-time dorm room at East Texas Tech.
Sheldon's penchant for adhering to a strict schedule at home in The Big Bang Theory was particularly difficult for Leonard for a couple of reasons. Firstly, they live with each other, so he was constantly subjected to it. He couldn't even use the bathroom whenever he wanted because they also had guidelines about who can use it at specific times and for how long. This was tricky since he's lactose intolerant who couldn't give up dairy. Leonard was also limited in his options when it came to the food they ate at home — something that the rest of The Big Bang Theory's Pasadena gang was subjected to as well. Sheldon assigned a cuisine or type of food for each day of the week, and while it helped them get into a routine, they grew tired of it eventually. Secondly, Sheldon imposing a strict schedule in Apartment 4A forced him to be less spontaneous, especially when it came to his dating life. This is why seeing Penny was easier since he wasn't forced to bring girls home: he could just cross the lobby into her apartment.
For someone who's obsessed with being organized, it's interesting to see Sheldon complain about having to make a schedule for his college peers. After all, he thrived in doing it for him and Leonard in The Big Bang Theory. In any case, since he discovered that his dorm room wasn't really being used to study, he's decided not to lend it to anyone else.
Young Sheldon season 5 airs Thursdays on CBS.