I love flying on Saturdays.The airports tend to be mellow and there are often fewer lines, especially in the late afternoon and evening. Restaurants and lounges are less crowded, and honestly, a lot of staff members just seem to be in a happier, more relaxed mood. One Saturday last month, a shuttle bus driver on the verge of retirement told us all her life story. It was delightful!As a Houston-based United Premier 1K traveler, upgrades are an important perk to me. And my batting average on Saturday has not disappointed.Want more airline-specific news? Sign up for TPG’s free new biweekly Aviation newsletter!For instance, I’ve flown on a Saturday from Houston (IAH) to New York (LGA) to visit my family a few times in 2021. I have been upgraded every time. It’s a different story on the return flight, often on a Monday: Just a single flight has been upgraded.When my girlfriend, a lowly Premier Silver, flew solo from Houston to New York on the Saturday after Thanksgiving, even she got upgraded.Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.Saturday is not an important day for business travelers. While they might go through TSA checkpoints and board aircraft more efficiently, they also compete for upgrades.Upgrades seem more abundant on Saturdays, when there are fewer business travelers. (Photo by Zach Honig/The Points Guy)Business travelers, of course, are the final, missing piece of the equation for airlines to return to profitability.More: Southwest wants business travelers and will double down on them as it recovers from the pandemicSo far in the fourth quarter of 2021, Saturday volume at TSA checkpoints is about 10% below the average volume. Sure, it’s not as low as Tuesday volume, which is about 15% below the fourth-quarter average, but business travelers fly on Tuesdays. (For the fourth quarter of 2021, Wednesday’s screening average — another quiet day — was about the same as Saturday.)Of course, there is a bit of a downside to traveling on Saturday: fewer choices. In December, the three largest U.S. airlines (American, United and Delta) combined have 49,574 flights scheduled on Saturdays, according to Cirium schedule data. By comparison, they have 72,584 flights scheduled on the busiest day of the week this month, Thursday.But to me, it’s a small price to pay. For better upgrade odds, mellower airports and more cheerful staff members, try flying on Saturday the next time you have the flexibility to.