Mares presented for inspection are not turned loose. Even for the MPT, they are first shown in hand before they are turned loose. The purpose for that, at the MPT, is to see their gaits when free, in order to compare what they show under saddle. Basically, the more they show under saddle, the more rideable/trainable they are deemed to be. If they show less under saddle than when free, they are not showing much rideability.
If you cannot run fast enough, or are not skilled at presenting a horse with big movement in hand, it is best to hire a professional who can do this to show your mare off to her best advantage.
Tranquility Farm - Proud breeder of Born in the USA Sport Horses, and Cob-sized Warmbloods
Now apparently completely invisible!