Can only relate to own exp. last autumn (in the north, and also on a FRI): due to the so many strikes of angry jolly workers there is since many yrs a law that stipulates there should be a MIN level of service to not disturb the other jolly workers too much in reaching their job. That mostly peak-hrs and for regional trains- a garanteed MIN service on all lines-with bus if it cannot be done on rails.
In my own exp these were indeed clearly posted etc on the screens that day-except that none was reasonably on time. But around half of normal service ran (never no checks on those days in general), so with plenty of time it was possible. It also seems from other reports there is often a very big difference between the fancy hi-speed FREcce etc treni and the locals. As a general rule its most by union-and there are several, which are discontent enough to call out a strike. Unions may differ a lot into what regions they are strong-or not.
Sorry-this remains a bit vague but thats often the situation as it is there.
