In the training world for some reason “maintenance” carries a negative connotation. But there are many reasons to move almost permanently into a maintenance phase for some athletes.
The primary reason you may go into a style of training like this is because you don’t need to develop as much anymore. Once you reach a strength, size, mobility, weight, muscle mass, endurance, etc your goal is to keep it. It is much easier to maintain this than build it.
It can feel like moving the earth to build the strength to squat a certain weight. However, if you train consistently you can keep this strength fairly easily. The same is true with many other athletic factors. Once you reach these top goals your plan should adjust to maintain them while focusing on other needs that were ignored.
Inevitably as you worked on these top priorities you left other aspects of your training or life in the rear view. Now that you can spend less time focusing on your original goals it is time to bring the others areas up to par. This benefits not only your sports performance but your overall well being.