I have done a lot of photo shoots over the years and I do prefer an escort accompany the model. Often a model will bring a friend or two who is supportive of the project and will act as a MUA (make-up artist). Many that have been on my shoots have been very helpful with posing suggestions and other ideas.
Some models have brought fathers/boyfriends/brothers and uncles. I don’t mind and like someone watching my back espeically on a photoshoot in Lummus Park where the temptation to snatch my Nikon might be too strong for someone to resist. It already happened one time.
I have found that the model will be a lot more relaxed with an escort.