Consistent practice is key to becoming a master.
You can visualize improvement as the functional consistency of your actions, or as the shingles on the roof of your house. They keep the negative aspects of weather away. Just like the take the negative regression away from your life progress.
In simple terms you can only move in one way, there is no stopping to maintain. You either make progress or you lose progress, which sounds worse than it actually is. However it can go in a spiral, for good or bad.
With strong Self-Improvement you can protect your Self-Development, allowing for exponential growth.
If you have poor habits for contiguous improvement, then you can have a regression whirlpool, driving you backwards in progress.