Distributive frequency (om de)

To express a recurring interval in Dutch, use the phrase om de followed by a number and a unit of time (or distance).

every (at intervals)
om de

Place om de directly before the amount of time.

I go to the physical therapist's practice every two weeks.
Ik ga om de twee weken naar de praktijk van de fysiotherapeut.
We go to the practice every three days for the ointment.
We gaan om de drie dagen naar de praktijk voor de zalf.

Units of time

Just like in standard counting, most units of time like weken (weeks), dagen (days), and minuten (minutes) take their plural form after a number.

The physical therapist stretches my shoulder every ten minutes.
De fysiotherapeut strekt mijn schouder om de tien minuten.

However, uur (hour) is a common exception. In Dutch, uur remains singular when used with a number.

Due to the pain, you must stretch your knee every two hours.
Vanwege de pijn moet je je knie om de twee uur strekken.
You apply the ointment to your shoulder every three hours, so that the pain disappears.
Je smeert de zalf om de drie uur op je schouder, zodat de pijn verdwijnt.