1.   Albatrosses never come to land except once every two years, to breed.

2.   Sampling frequency was once every four seconds.

3.   The frequency with which arrhythmias and syncope occur varies considerably, from several times a day to less than once every several years.

4.   The planet turns round once every twenty four hours.

5.   My mum, erm, once every two weeks.

6.   And God help you if one L is to Auburn more than once every two or three years.

7.   Asphalt driveways should be resealed about once every three years to maintain their solid-black appearance and protect them from cracking and oil damage.

8.   At first, Karina called home every week, but the pace of the calls then fell off to once every month or two.

9.   A player with this sort of impact on the game might come around once every couple of decades.

10.   About once every other month, an odd assortment of local singers meets to take turns re-interpreting the songs of some pop-music luminary.