Given that aired 279 episodes during 12 seasons, it only makes sense that strict rules needed to be followed behind the scenes in order for things to run smoothly. As we're going to reveal in the following, that was especially the case when it came to the production of the show and lines written by the writers for the cast. Some sitcoms were open to changing lines such as , however, that wasn't the case with , and we're going to reveal why.

In addition, it seems like the showrunners were very sensitive when it came to the look of their characters, particularly the main four guys, Sheldon, Leonard, Howard and Raj.

We'll take a look at a key rule the four were following throughout the series. In addition, we'll reveal a request Johnny Galecki pitched for the appearance of his character Leonard on the show, and how he was able to get the okay for it despite initial pushback from those behind the scenes.

Sticking To The Script And Avoiding Improv Was A Key Rule Behind The Scenes Given How Tight The Shoot Schedule Was

In the past, sitcoms used brilliant improv moments to fulfill certain scenes.

That was the case on , as the directors behind the scenes would modify scenes based on the audience's reaction. However, that was not the case on . There were the odd moments of improvisation that were kept in, but for the most part, sticking to the script was necessary.

given the strength of the writing team.

"My impulse is always to try to contribute, but very quickly, I felt that that wasn’t necessarily the way that this show worked. n some ways, it’s a great harmony. They are fantastic. It does take a little bit of courage to say, “Hey, how about this?,” but that’s just because they’re so great at what they do.

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throughout his stint on the show, "The cast doesn't improvise. Because we don't need to, the writers are so good that if a joke doesn't hit, the writers will converge on the spot and within three minutes have it rewritten—so it is funny."

Kunal Nayyar also added that he didn't improvise his lines or joke around during scenes, especially given the time constraints involved during a tight shoot. Shooting 279 episodes, clearly things needed to run smoothly from a production standpoint.

The Men On The Big Bang Theory Were Discouraged From Growing Beards

Tampering with your look was a major dealbreaker for those on Fans have noticed that throughout the seasons, Raj, Leonard, Sheldon and Howard never have beards or facial hair, aside from the episode that sees them return from their expedition. It seems like this was purposely done for the men of the show to stay in character and keep their looks for the show.

Fans also caught on to the fact that a lot of the main cast members would grow beards when the show wasn't filming, taking a break in-between seasons. That was especially true for Johnny Galecki and Kunal Nayyar. Perhaps if the two had it their way, they'd be rocking facial hair during the

but clearly, it was not meant for their characters throughout the 12 seasons on the show.

Wardrobes also stayed consistent and rarely did the main four ever sway from their particular styles.

Johnny Galecki Got His Way With A Particular Appearance Request, Despite Hesitation From The Producers

Johnny Galecki had a vision for the look of Leonard and it involved glasses. During the early stages of the series, Galecki wore his glasses while practicing lines. It seems like the showrunners thought he was wearing them out of necessity, but not for the show.

, but he had other plans in mind.

“We rehearsed the first episode for about a week and a half, and when we started to shoot, they said, ‘Well, you’re gonna take your glasses off, right?’ I said, ‘No, I want Leonard to wear glasses.’ They said, ‘Oh, we just thought you were wearing them as Johnny for rehearsal all week,’” said Galecki with

Things were made that much more complicated when Galecki's lenses were causing a glare during the shoot. Instead of giving up on the glasses, Johnny wisely popped out the frames and as they say, the rest is history and the actor was allowed to keep the glasses for the entire series. Had Galecki not pushed for them, he could've looked very different throughout his run as Leonard.