Overcrowding in the emergency department (ED) may be caused by internal or external sources and is closely connected to the duration of stay, or LOS. Understanding the primary factors influencing the LOS is crucial for establishing a hospital’s performance and dependability and for lowering it. This study intends to compare the outcomes gained by examining the LOS procedures in three different hospitals. Data were gathered from the Naples-based A.O. Federico II, in the following section referred to as H1. The results were compared to those from the examination of data from two additional hospitals, the “San Giovanni di Dio and Ruggi d’Aragona” of Salerno, namely H2, and the “A.O.R.N. Antonio Cardarelli” of Naples, namely H3, as described in the work by Valente et al. [1]. The best performance among the several linear regression methods used to process the data was assessed.