why add 个 here? why not 每晚上
And also; why is there no 都 after 晚上？For "I drink coffee every day" we are supposed to say 每天都 because it sounds more natural. But why not now?
Why not 我们的孩子每天晚上喝牛奶?
It didn't accept "我们孩子每个晚上喝牛奶" with no 的 after 我们