Strick style training should be the basis of every training regiment, simply because the potential for maximizing your training performance is based on the quality of each repetition. Bottom line, you're only as good as your technique Strict style training is the launching pad for the other two training styles, which simply means you must first learn how to perform each and every single exercise with perfect form and technique, before incorporating the other two training styles.
Loose style training, otherwise referred to as a cheat set is one of the best ways to break through stubborn training plateaus, in addition, a great way to extend a set. Loose style training should not be the main focus of a proper training program, yet it needs to be incorporated strategically over the course of the entire program for maximizing results.
Partial style training refers to an exercise that is never performed with a full range of motion. A partial repetition can be implemented in the beginning, middle, and end of each exercise. Partial style training can be used as a pre-exhaust, set extension, or finishing technique, based on the training objective. Utilizing these three training styles throughout a training regimen dramatically improves training performance which is the smart way to achieve your full potential for meeting training objectives. FYI, If your trainer doesn't know about this, they're most likely a faker.