I've got a English tutor and we had a session on English writing.
But he gave me a correction on my writing which is still confusing to me.
The practice lasted about three weeks, after which every team would do voice over in front of the class.
He said "three weeks" should/could be hyphenated, i.e "three-weeks."
That was confusing to me as I thought week is hyphenated in cases like
a three-week holiday.
Did my tutor give me a wrong answer or was it just me not knowing the rules?