Length of Time for Listing Agreements

I am curious about something.  I posted previously that I own three properties and might sell two of them.   One of the properties I plan to sell is in SW Vermont.   I chose the real estate agent because she is the one I contacted when I saw this property for sale on her website seven and a half years ago.   I liked her spunk and her responsiveness, so she was a natural choice when I decided to sell it.

She mailed me a large packet with pages to sign including a listing agreement.  I was surprised to see she wanted an agreement for a full year.    I had never sold property before, but this struck me as too long, so I changed it to five months.

What is the standard length for listing agreements?

Another issue is she told me she would send me back copies of all the papers I signed -- very clearly stated in her cover letter.    Now she wants to hold them until we have an agreement about the length of the listing agreement -- my own signed papers.

Red flags are going up for me, and I want to check my judgment about this.

Does anyone with more experience selling property have any thoughts to offer?