The Big Bang Theory and its spin-off series Young Sheldon aren’t releasing new episodes this week, and it’s all thanks to CBS’ scheduling. Both shows are currently going through very important runs: parent series The Big Bang Theory is preparing to end after 12 seasons, while its prequel spin-off is already being positioned to eventually take its place as the broadcasting channel’s #1 comedy show with a two-year renewal.

Debuting in 2017, Young Sheldon has mostly operated independent from The Big Bang Theory until last year’s crossover event. The offshoot tackles Sheldon’s years as a young boy growing up in Galveston, Texas with his family. The Big Bang Theory, on the other hand, continues its ensemble storytelling with arcs for all the other members of the Pasadena crew, although admittedly, between getting married and his potentially Nobel Prize-winning project, Sheldon and Amy have been getting a majority of the attention lately. Together, the two shows make up for the perfect comedy block for CBS every Thursday night.

However, fans will have to wait an extra week for new The Big Bang Theory and Young Sheldon episodes with the popular combo skipping Thursday, February 28. Instead, CBS is airing reruns for both shows: “The VCR Illumination” for The Big Bang Theory, while “A Research Study and Czechoslovakian Wedding Pastries” for Young Sheldon. What’s interesting, however, is that instead of airing back-to-back like their usual schedule, Young Sheldon is switching time slot with Allison Janney and Anna Faris’ Moms, going live at 9pm instead of 8:30pm. Fans are understandably frustrated about the almost weekly breaks since January especially with dangling plots waiting to be resolved for The Big Bang Theory.

However, as unusual it may seem, episodes of The Big Bang Theory have always been spread out after it returns from its mandatory winter break to land on a May season (in this case, series) finale. This is due to the approaching sweeps period between April 25 to May 22 (this year). Data collected during sweeps (scheduled also in November, February and July) are used by advertisers and stations to decide on the advertising rates for the rest of the year - the more viewers, the higher the price can be for advertisements slots. Since The Big Bang Theory is a ratings juggernaut for CBS, they’ve rarely skipped a week during these times, especially in the later seasons. The only reason that this has become quite an issue in season 12 is that, knowing it’s the show’s final year, viewers are more anticipative of what’s going to happen next with their favorite characters.

Considering that Young Sheldon is a tie-in show to The Big Bang Theory, their airing schedule almost always mirror each others. Additionally, being the second most popular comedy show only behind its parent series, that same principle about sweep period is also applied. This will more likely continue moving forward even after The Big Bang Theory is no longer on air.

With just eight more episodes left before The Big Bang Theory officially end, fans can expect a couple of more weekly breaks for both shows. No announced date yet when the series finale will be, but we know that final taping day is scheduled on April 30th as revealed by Kunal Nayyar (Raj). Given this, an air date for the final episode will likely be May 9 or 16, one or two weeks after it was shot (and still coinciding with the upcoming sweeps period).

More: Big Bang Theory Is Using Penny & Leonard To Distract From The Weaker Stories

The Big Bang Theory and Young Sheldon air Thursday nights on CBS.