“每个星期” vs. “每星期”

[Alchemist]

The first book I've learned Chinese from gives examples where 星期 is used with 个 before it (每个星期).

Now I have a new Chinese book that uses 星期 both with and without a measure word:

我每个星期有六节汉语课。

我每星期有两个小时辅导。

Is it correct to use 星期 without a measure word?

In this book there's another sentence that puzzles me:

中文系有八个班，九十多人。

Wouldn't it be more correct to say "九十多个人"?

[skylee]

You may be even more confused if I say that it is also OK to say -

我每星期有兩小時輔導。(no 個 after 小時)

我每星期有兩小時的輔導。(with 的 after 小時)

中文系有八班，九十多人。 (no 個 after 八)

There may be some sorts of rules here, but I am poor at explaining these things.

[Alchemist]

You may be even more confused if I say that it is also OK to say

Yes, thank you for making my doubts redouble.

[wisder]

This is the brachylogy.

中文系有八班，九十多人

八班is not correct. must with "个"

because before 班 can be a ordinal number or a measure word

they are different. 八班is a ordinal number and 八个班 is a measure word.

Only before 人 can you omit "个" .others are not in common use.

[Jose]

There are some nouns with which the use of a measure word is optional. A

good example is 小時. Both 三個小時 and 三小時 are correct. Note that if

you were to use 鐘頭 instead of 小時, then the measure word is required:

三個鐘頭.

I suppose we can regard 小時 as a border case, between time words like 天

or 年 , that go straight after the numeral, and others like 鐘頭 or 世紀

that are used with the 個measure word.

星期 is another border case, but I think it is more common to use it with

個than without it.

There are two other common words for "week": One is 週 (formal), which takes

no measure word, and the other one is 禮拜, which always takes 個. So, to

say "three weeks" you can say:

三週 (formal)

三星期

三個星期

三個禮拜 (informal)