Earlier quoted context omitted.
In my experience (running a Windows vm) the forced reboot is more like every two months. Also they have a feature called availability sets where you can load balance two VMs and they guarantee that one of them will always be up. Edit: Looking back at my email history, it's much less often than that. The interval between the previous two reboots was 6 months. They also gave about two weeks notice when it happened.
I just had this happen recently and there was no warning. Perhaps it depends on the "level" of services you are using. My instance was just an "extra small" vm.
The primary workload we were running was video game servers. The server stores all state ephemerally in RAM tied to the process. When it goes down, that play session is over and all players are booted. This was just a constraint of the software that we had to live with.
What I was looking for was some kind of heads up so that I could at least try and take down the process gracefully, but that wasn't possible.
As said, this was a while ago. Hopefully the situation is now different.