Why is the z 106 train always late?

Large passenger flow, long time to get off. Because the Z 106 train is a local train, the stop time of the station is about two minutes, and some stations have a large passenger flow, so the boarding and alighting time starts to be extended, and then it will be delayed in turn, so the reason why the z 106 train is always late is because of the large passenger flow and long alighting time. The predecessor of Z 105/ 106 train was 189/ 190 train running between Jinan and Urumqi. On June 1999, the train diagram of China Railway was fine-tuned, and the Jinan-Urumqi 189/ 190 train and Lianyungang-Korla 192/ 189,190//KLOC were added.