In stark contrast to its later seasons, the first entry in The Office‘s nine-year run only boasted six episodes. Based off the original British series, the celebrated American version outruns Ricky Gervais and Stephen Merchant’s original series in episode count by the end of its second installment. Despite that, The Office‘s first season is exceptionally shorter than its counterparts. While the British series established the mockumentary format, the American version refined the series, which caused some significant differences between The Office UK and US versions.

https://screenrant.com/the-office-season-1-why-so-short-6-episodes-explainer/