In The Red-Headed League why do the criminals plan to commit their crime on Saturday?

In "The Red-Headed League," the criminals plan to commit their crime on Saturday because they anticipate that the absence of the Red-Headed League's activities on that day will provide them with the perfect opportunity to dig a tunnel from their hideout to the bank without being detected. Saturday is chosen specifically as the League is closed, allowing them to execute their plan without interference. Additionally, it allows them to take advantage of the weekend when the bank would be less monitored.