Thanks Avanar and Yarofrey, I'm aware of this work around and I have used it very often.
I would like to be able to do without it, because it's very bad for optimization. Each time I used it, it's 6 block or often more, whereas I could only use one if I could control the internal diameter of the hollow blocks.
Edit :
Take, for example, this wagon wheel published in July 2024. It has 360 blocks; I find that far too many for this object. However, it's a focal point on a cart that has a significant impact on the overall perceived quality of the object, which is why I don't want to degrade the detail and I don't see how to optimize it without doing so. If I could control the internal diameter of the hollow blocks, this same object, with equivalent quality, would easily drop below 50 blocks, representing an improvement of at least a factor of 7.
So yes, this wagon wheel is a somewhat extreme example of the benefit of having control over this parameter, but it's a very real one.