When a patient comes into our orthodontic office they are paying for a service. Your orthodontist is going to give you the result while utilizing the tools necessary to get that result. If the doctor can give you the result with a clear tray from company A or B shouldn't matter, both companies make trays that exert a force on the tooth to get it to the desired position.
As for treatment time, the process of moving a tooth through bone takes time. Generally, the farther a tooth has to move the longer it takes. Orthodontics accomplishes this movement by putting a force on the tooth to get it to move. If there is no force then there is no movement. An orthodontist uses brackets (lingual or traditional) with wires, trays (invisalign or clear correct) , appliances, and sometimes retainers with springs to place the ideal force to move a tooth. Your orthodontist can reduce treatment time by making sure you do not have any months where there is NO force on the tooth. Visits to the office are generally to make sure the teeth have the correct force and direction. If one method was better at moving teeth and reduced treatment time, then most likely other methods would be considered outdated and not used anymore.