One of my major interests and goals in the study of bonsai is growing a tree from start to maturity, and see how well I can do it. Over the years that I've been starting black pines from seed, I've learned a lot about growing, reducing, and removing a sacrifice branch in the development of a good bonsai tree.
I originally thought that the sacrifice branches on these trees would just run on until the trunks got to the size I wanted. I revised that plan when I realized that to maintain the balance between the branching that I'll use for the final design and the sacrifice branch, at times I'd have to reduce the sacrifice branch, either by removing the central strong leader, or by removing side branching. If left unchecked, the sacrifice branch would both shade out the lower branching and also weaken it by hormone inhibition.
I also need to take practical considerations into account. For ground growing, the sacrifice can be allowed to grow quite tall because the tree is unlikely to blow over. Instead of removing the central leader you can reduce the top by removing the side branches. However, for container growing it is impractical to allow the sacrifice to continue to get taller and taller; eventually the tree will tip over - even in a gentle breeze. For my 2006 batch of Japanese Black Pines I had already removed the central leader in 2011. While this slowed the wood production, it increased the vigor of the smaller branches that are eventually more important.
The small branches that are being maintained for the final design on this tree are strong enough to decandle. But, the sacrifice branch also needs to be reduced or hormone inhibition and shading will make these branches too weak.