Only ikkyō through gokyō are considered fully "standard" names for aikidō techniques, as these five names were inspired by the original five lists of techniques (ikkajō through gokajō) in first Daitō-ryū transmission scroll, the Hiden Mokuroku
That being said, "rokkyō" has become a fairly popular alternate name for the technique also called "hijishime" (amongst other names).
After rokkyō, it is not very common to call the techniques by numbered-names. Doing so seems to be isolated to a small number of lineages of certain shihan (I am not sure which ones). I have only ever seen one Youtube video that identifies a technique passed rokkyō, that one being "nanakyō".
On this website, there are two articles describing these extended, numbered-named techniques. I am not entirely certain, but I believe the two articles were written by practitioners of two different lineages. Both authors have since passed away.
, by Rocky Izumi
Beyond Yonkyo (Armed)
by Dennis Hooker