And yet, the early Friday getaway is becoming something Chicago's Metra Commuter Rail service recognizes, and shuffles its schedules to accommodate, at least before the long weekends. The carrier anticipates more family outings, all summer long. "Children ages 11 and younger can ride Metra for free from Memorial Day — May 29 — through Labor Day — Sept. 4." (Via Destination: Freedom.)
Generally, the Friday-before-a-Monday-holiday schedule involves running some of the skip-stop trains from Chicago earlier than they normally would, which entails issuing a special Friday schedule noting the additional service, and corresponding cancellations of later trains. "For example, on the Elburn line, the skip-stop train for LaFox that normally leaves at 5.09 is replaced by a LaFox train, first stop Elmhurst, earlier in the afternoon."
We'll know that a half-day of work on Friday is becoming a thing when the regular timetables identify some trains as operating Monday - Thursday only, with Friday-only departures concentrated around noon. That was the practice on a lot of railroads during the Depression and immediately past World War II, in which there was a "Weekday" schedule with some Monday - Friday trains and Saturday-only departures around noon. Then there was a Sunday schedule, which sometimes meant no trains run, and sometimes there was a very different schedule. We see a survival of that on Amtrak's Downeaster to this very day.