Period stopped my first depo shot. randomly got one 10 years later and still on depo. is this norma?

The Manufacturer advises that you should not be on Depo Provera long-term, unless there are no other options for contraception, in which case, you need to take a break from it, every couple of years. This is in the drug information leaflet.
When we don't do that, it can lead to such irregularities with menstrual bleeding.
I'd suggest your body needs a break, if you've not been having them. This is something that happens to many, when they do not do this (me included).

The short and simple answer is yes- that is absolutely normal. I've been on Depo since I was 17 (turned 40 this year- so 23 years!) and from my experience, there is no pattern necessarily to it. For me, it may have seemed like it was once every five years- then it was eight years- then the following year after that it was 2 or 3 times in that year. But even on those RARE occasions, flow/ duration wasn't typical (not even consistent enough to buy products). Since you are a long-hauler like me, I have lots of questions to ask you as well and would like to compare notes. I've noticed over the years when I do get it, I try to take note as to what may have been a trigger-- like a life change / stress!