If you truly want to stay shohin size, I'd consider cutting all branches off every fall and let new ones form each year. Or, if you like the silhouette prune the branches at bud break. Leave one of the buds that people are complaining about for larger trees and you should get an in scale branch in a week or two. At shohin size, and the rate these guys grow, it will be difficult to keep branches in scale otherwise. You'll likely be in a constant battle of fighting new leaders too as they are pretty apical dominant...they want to be tall trees!
Also, not all the back buds grow out. If they are shaded, they tend to stay dormant.
One of my "covid sanity projects" is to grow a shohin sized dawn redwood forest from seed
Many of the veterans will find this progression ridiculous...that's fine. It kind of is :D But I'm also bored and am in the habit of starting much of my "from seed" in the fall anyway so I'm going for it! The last time I started a batch of metasequoia glyptostroboides seed was 2 years...
www.bonsainut.com
I've been posting monthly updates just for kicks to watch this silly little thing grow! I've done everything "wrong": planted seeds in winter, trees live 100% indoors, yadda, yadda, but dawn redwoods are very maleable and it keeps me entertained
It's getting big enough already that I'll need to start pruning branches to keep it in scale!
It's a silly project, but I think it will illustrate what others have said...it's a shaggy tree to keep in scale at shonin size.
But give them space and water and they can dwarf your tree in 2 years, easy. So they can be a quick turnaround to try again if you screw something up