Why does this express train take only 6 hours from Hangzhou to Chongqing?

Hello, Zhejiang SF Express Hangzhou Central Distribution Center is located at SF Base at the east gate of Yongsheng Road, Xiaoshan Airport, Xiaoshan District, Hangzhou. From Hangzhou urban area to Xiaoshan airport SF distribution center base, by air to Chongqing Yubei SF distribution center, then by land to various distribution stations in the urban area and by air to the recipients.