Before the advent of the ACH, it would typically take a week for an employee to be able to access the funds from a paycheck. It would require first a trip to the bank during business hours to deposit the paycheck and then several business days for that bank to complete the time-consuming process of collecting the funds from the employer’s bank.
4 With the advent of ACH, an employee could expect to access their pay from their bank on the same day it was deposited electronically by  3  Jeffrey Bucher, “The Check,” (remarks at the Annual Meeting, Bank Stationers Association, Colorado Springs, CO, June 4, 1973), https://fraser.stlouisfed.org/title/931/item/36180.