It sometimes takes a bit of experience to get good divisions consistently, and success rates will vary depending on the species and other factors as well such as temperatures. Here's just some of my results.
Phyllostachys parvifolia: I took 14 divisions 6-8ft tall and potted them into 5 gallon containers. Since I took large root balls with lots of rhizome and roots on both ends, it looks like all of them made it, and I have most of them already adapted to full sun only after 4 days of division.
Here's one of the tiny rhizome divisions taken last year that is finally shooting. It is one of the ones that hardly had any root hairs, and it's pretty impressive that it could establish itself.
I also have some of the divisions where I force whip shoots through the drainage holes of nursery pots. This usually gives me a medium or small sized division which works every time, especially with parvifolia which is quite easy to propagate.
I can also do the same with atrovaginata or any other bamboos that generate rhizomes/ whip shoots.