Bus timetables can be confusing. The key words to know are:
Feriale - work days, including Saturdays.
Festiva - Sundays and holidays
Gornaliera - Daily
Note that the 5.50 Feriale is Soppressa dal 03 Agosto al 31 Agosto 2013. Which means that the 5.50 service does not run (it is suppressed) between 3 August and 31 August. Most Italian firms shut down for much of August. There wouldn't be much call for the 5.50 taking people to work. So if you are standing in the middle of the blazing August heat waiting for a bus, check the timetable.