Train for your own arena...
In the world of martial arts, self defence, combat, fighting and survival there is always the discussion about what constitutes 'real' or effective training. Examples of not only how you train, but who you train with, where you train, what you have experienced in the 'real world' scenarios etc are always bandied about with varying levels of enthusiasm / aggression.
If you do traditional martial arts people want to know who you trained with, how long, is it true to the original or have you adapted it in any way. If you train in reality based self defence there is a lot of have you used it, does it work at full speed, who you trained with, how often do you spar 'for real'. If you are military based combat trained its all about which army / regiment / deployments / how long served etc. If you do sport competitive martial arts its all about ring / cage work, who you've trained with, what you've won, and so on.
As you can see the chances of pleasing all the above criteria are practically impossible. The point of all this is to highlight that you train for your own arena, your own circumstance, your own interest. There is no point in learning competition martial art in the military as you need to be able to use weapon systems under stress and with a high level of cardiovascular endurance. There is no point learning sword work if you are a doorman in a high crime area, and there is no point learning how to snipe a target at 500 meters in a concealed position if you are interested in forms and kata completion.
Where does that leave the art of Ninjutsu then? We are no longer in feudal Japan, and the need for operation intelligence officers are limited to government work. But the skills learned in Ninjutsu are key to avoiding conflicts, evading pursuers, reading situations (intent) and the use of effective principles whether unarmed or with any weapon that comes to hand (hence the many and varied weapons trained in).
If there is an underlying guiding principle to Ninjutsu it is survival - not winning, not getting a trophy, but survival. That can mean just leaving before the fight starts, that can mean controlling an opponent for the police to arrest, that can mean as a last resort the application of severe trauma to survive. It has to be adaptable as there is no predictable events in a conflict, so we need to adapt to what we are presented with.
Don't worry about what the other guys are doing - train for your own arena.