Companies use a fiscal year and fiscal periods that best suit their business.

Retail companies often use a fiscal year that nominally starts in February, but on a week boundary so that the fiscal year always starts on a Monday, with the actual start of the fiscal year being the first Monday on or before February 4th. The reason they start the fiscal year with February is so they can include the busy Christmas shopping season, along with the large number of returns of Christmas purchases that happen in January.

Some retail companies use fiscal periods of 4 weeks then 5 weeks then 4 weeks to give 12 fiscal periods and 4 quarters of 13 weeks, while others use 13 fiscal periods of 4 weeks. Since the fiscal year only has 364 days, every few years they have to add an additional week to one fiscal period, usually the last, to keep in sync with the Gregorian calendar of 365 days.

Retail fiscal years were my first encounter with a fiscal year table when I developed a database for a retail data mart product.