Here is a recent email from a voiceover neophyte (newbie) and my advice.

2022-12-15T08:52:07-06:00

I believe you should be prepared and always try to put your best foot forward, especially with a voiceover demo. If it turns out to be substandard because of lack of preparation, training, production quality, or because you “quickly try to put it together”, the demo will reflect these factors you may make a poor first impression that could hang with you for a while and work against you.