How often (de multe ori, de regulă, din când în când)

How often?

You already have the one-word answers: mereu, des, uneori, rareori, niciodată. Romanian also says how often with fixed phrases. Counting times uses dată for one and ori for more: o dată (once), de două ori (twice), and so de multe ori (many times, often). Its superlative, de cele mai multe ori, means "most of the time". De fiecare dată is "every time", and din când în când is "from time to time".

Whenever

Ori de câte ori opens a whole clause, just like de fiecare dată când: ori de câte ori plouă (whenever it rains). When that clause comes first, put a comma after it.

As a rule

De regulă is a close partner of de obicei (usually) and stresses that something follows a pattern. Do not mix it up with în regulă, which means "all right".

Day after day

Repeating a noun around de describes something that goes on and on: zi de zi (day after day), an de an (year after year). În fiecare zi simply says "every day"; zi de zi adds the feel of a long, steady routine, so it sits well with the tot you just learned. Pas cu pas (step by step) uses cu instead and means slowly, one stage at a time.