Well, it may not be for everyone. If you don't have anything on the line for your events, then train however you want. No one's got a gun to your head.
LSD rides build your endurance systems, but not speed or power. So there is some logic in doing LSD rides, if you're participating in endurance events, as it will presumably prepare you better for that type of event. But if you don't like to do that kind of training, and you're not getting paid to ride/don't have any other stakes in performing well, do what you want and have fun!