I sing regularly at an open mike in a coffee house, and typically I'll be told that I can have 20 minutes.

Now my songs are usually fairly short, and 20 minutes, with introductions, means about six songs.

I sing with guitar or banjo much of the time, but in a six-song set I'll probably sing the second and fourth or fifth song unaccompanied.

Some of my songs are such, and my interpretive style is such, that I cannot imagine an instrumental accompaniment doing anything but getting in the way of what I want to accomplish.

Your mileage may vary.

Dave Oesterreich