My local NAPAs have one in spring (around 2nd week of March) and one in late fall (around 3rd week of October), and since 3 of the 4 stores within 20 minutes have different owners, the sales are usually staggered by a couple days, leading to about a 15-18 day window.
My favorite 7055 filter goes for like $3.73 during this sale, and 1372s go for about $4.08. I wait til the sale, then buy about 6-8 of each to cover my usage plus F&F.