Once a Week -에 한 번

일주일 is 일 (一, “one”) + 주 (週, “week”) + 일 (日, “day”). Together, it means one full week: a seven-day period. Don’t add the syllables as “one week plus one day”; the last 일 is part of the word for the week-long period, not an extra day.

번 already showed up in 일, 이, 삼 naming a number, 삼백사십 번, “number 340,” using Sino-Korean. Here it means “times” instead, and switches back to native numbers: 한 번, 두 번, 세 번. Same word, same spelling, a completely different number system depending on which job it’s doing.

Leading with the frequency phrase isn’t mandatory, Korean word order is flexible, but it’s overwhelmingly the natural default. Burying 한 번 in the middle of the sentence isn’t wrong, it just reads like you’re adding an afterthought instead of stating the pattern up front.