Are they correct?

[lisa666]

Hello everyone
Could you please tell me whether the answers to the questions are correct?
Thank you.
1. Are they often busy? No, they often aren't. / No, not often.
2. Do they usually work late? No, they usually don't. / No, not usually.

[Bennevis]

I'd say:

1. Are they often busy? No, they aren't often. / No, often not.
2. Do they usually work late? No, usually they don't. / No, usually not.

P.S. The word in bold is stressed.

[Tdol]

I would answer this way:

1. Are they often busy? No, they aren't. / No, not often.

[Raymott]

Hello everyone
Could you please tell me whether the answers to the questions are correct?
Thank you.
1. Are they often busy? No, they often aren't. / No, not often.

Also you should be aware that there is no contradiction between:
"They are often busy" and "They are often not busy."
But there is a contradiction between:
"They are often busy" and "They are not often busy."