You can guarantee that your shrubs will at least have the opportunity to grow to their genetic potential within the limiting effects of other cultural factors with regular attention to root work, which includes root pruning & regularly changing the soil. You can guarantee that they won't have that opportunity by trusting the tree to nature's course and ignoring the root work. To illustrate that point, I can say that I have never seen and can't imagine a tree in the same container for 5 years or longer that is growing to it's potential. If there are, it's a safe bet they started out in a VERY large container in a VERY fast soil so the soil/root mass is still not congested to the point it could be lifted intact from the container.

I don't think we need to put a 'right/wrong' label on anything any of us do insofar as our efforts at husbandry are concerned, but we could sure have a discussion about the comparative degrees of good that range through poor - not so good - ok - better - approaching best. Having grown hundreds and hundreds of trees & woody plants in containers for more than 20 years, I've decided that highly-aerated and long-lasting soils are the media that produce the best growth with the least effort and the widest margin for error, even in consideration of the fact that initially they're not the easiest soils to put together because of some initial difficulty in locating the best ingredients (but not always - I have and didn't have any trouble).

For some more direction & to review the discussions & results of others, you could try reading through the link I left below. At the end of the opening post, you'll find a link to the previous thread with additional discussion, if you're interested.

AL

Here is a link that might be useful: More about trees in containers if you click me.

Thanks Al. Been reading a lot of your posts here.

Hadn't seen that link yet -- I'll get on it.

You are already doing everything right. Maybe you might want to move up to mastering how to root Dogwoods.