The File Watcher Task is a new one for me; could be useful in future. At present, my ETL tasks run once or twice a day and as Phil says above, tests if files are present, loading them if so.

Although I do use the Flat File Source component, I often have to replace it with a Script component written to deal with real files which often have bad rows or other oddities which confuse the standard Flat File Source. With Flat File Source, your imported file must always have the number of fields expected, and if comma-separated it can't have embedded quoted commas - e.g. a field like "19, The Strand" or """The Elms"", 4 High Street" will confuse it.