Thinking of hard or soft cane Dendrobiums?
Nobile types - I have the white nobile which I just posted, I don't stake that at all. But, I find that those first grow straight up and then have a very good chance to kink/break as they get too heavy. So what I do, I attach a little weight to the tip of the canes, then they will gently dip down without the break when they reach that stage. ( Btw mine is growing without pot, I just attached that first piece to a piece of tree fern) Dendrobium anosmum is grown many times similarly since the canes can get really long and then there is Ricardo who mounted them upside down.
http://ricardogupi.blogspot.co...
Here he talks about the in a soda bottle upside-down culture.
http://ricardogupi.blogspot.co...
You have to dig around a bit on his site, there is a huge amount of information in those pages, including comments.
I can't answer your question precisely, but I have seen some monster plants with really long canes.
