Yes that is true. Especially on tile roofs, with iron roofs...

Yes that is true. Especially on tile roofs, with iron roofs enough air enters the roof area from the ribs in the iron, so not a necessity, but the more the better in this case. Also great for getting rid of the humid air from forming condensation on the underside of the iron which will in turn eventually leed to rusting geting a hold alot quicker.

Regards The Tinopper