MMA is coached in various ways. There's no one 'right' way. Commercial gyms will have separate classes in stand up ( Muay Thai or kickboxing), grappling (usually BJJ) and often a traditional martial art or two plus a boxing class. They are likely to have fitness classes too, this, obviously, makes the money for the owners. Most would be MMA fighters find they have to train separate classes and then probably have private sessions to put it together, some gyms have 'all in 'MMA classes though but to be commercially viable this would probably be once or twice a week. Would be fighters will have to go through their separate classes learning everything in that style, not necessarily a bad thing though.
For established fighters the training regime is different, they aren't restricted to having to take classes, they have sessions throughout the day with coaches interspersed with strength and conditioning, stamina and fitness training. this is where fighters can pick and choose what techniques they find work and they can do. The established people can meld all their techniques into the whole while being coached by an expert MMA coach, they will learn ringcraft, listening to corners (!) and all things pertaining to fighting. This however is no different from any sport. The commercial sector which is where most people start is the same place where non MMA fighters go. Once you show talent things change.
