Grammar JLPT Level N4 - Lesson 6

Structure of 毎(ごと)に:

Verb + ごとに
Noun + ごとに

Details about 毎(ごと)に:

ごとに is an combination of the noun ごと, and the particle に. Together, they are used adverbially to express that something happens 'every (A)', or 'at intervals of (A)'. ごとに may be used after any verb (usually in non-past form), or noun.

私(わたし)は彼(かれ)に会(あ)うごとに、「何(なに)を食(た)べたい？」と聞(き)かれます。
Everytime I see him, he asks me 'What do you want to eat?'
私(わたし)は3時間(じかん)ごとにお菓子(かし)を食(た)べます。
I eat snacks every 3 hours.

Although ごとに may be used after verbs, the most common use is with nouns, or phrases that finish with nouns.

毎(ごと)に

Usage Notes for 毎(ごと)に:

ごと is the 訓読(くんよ)み (Japanese reading) of the kanji 毎(まい), which means 'every'. This fact will be important when trying to remember the difference between ごとに, and おきに, a similar grammar point which also means 'every', but focuses more on 'intervals'. Due to おきに focusing on the space between 'each', there are sentences where おきに and ごとに will have different meanings.

私(わたし)は一週間(いっしゅうかん)ごとに実家(じっか)に帰(かえ)ります。
I go to my parents' home every week. (Every single one)
私(わたし)は一週間(いっしゅうかん)おきに実家(じっか)に帰(かえ)ります。
I go to my parents' home every other week. (Every single interval of one)

Here, we can see that ごとに will mean 'every week', but おきに will mean 'every second week'. due to there being a 'one week interval' when おきに is used. To make things easier, these two expressions can be remembered in the following way.
(A) ごとに = Every (A)
(A) おきに = Every spaced repetition of (A)