Why is this even something that is an issue? A while ago I watched a Show called Rage of Bahamut: Virgin Soul. There came a point watching that show I realized I was missing a lot of information that wasn't present in relation to characters, so I looked it up only to find out it was a sequel to a previous show. While it's true the story was self-contained, the reason to care about many of these characters was non-existent in the actual show, meaning you would need to have watched the previous show to be able to care at all.
But here is the thing, unless you are researching shows in depth before you watch them, you would have no idea going in that Rage of Bahamut: Genesis existed. That said, there is at least a consistent naming theme here, though it's still something that bothers me. The thing is it gets worse with other shows.
I am currently watching W'z, and this show is a sequel. The name of the show it is a Sequal too? Hand Shakers. Do you know how I know this? A characters name was mentioned, and it slipped my mind who it was so I googled it real fast. Turns out the name mentioned was the main character of the last series. Now, so far I am getting the impression you don't need to have seen the past series at all, and it's much better set up then Rage of Bahamut because I”m already getting reasons to get behind these characters and care about them.
Why couldn't Rage of Bahamut: Virgin Soul, a show that really does need you too have seen the first series to care about it, not come with the title Rage of Bahamut II: Virgin Soul? Or in the Case of W'z, just call it Hand Shakers 2: W'z? When I enter into a franchise, I don't want too suddenly pick something up and realize halfway through the show I am entering into something that is even a franchise, to begin with. I am left here feeling like I am missing out on something.
Hell, my first foray into Harlock was Queen Esmeraldas, so this isn't really a new problem. Just give me some kind of indication its part of a franchise. Especially since W'z, the one mentioned above, kind of still spoils things that happen in Hand Shakers, even if the story is, in fact, stand alone. Now if I ever want to go back and watch that show, I am going to have some upcoming twists ruined for me.
Numbers are not your enemy Anime. Please stop coming up with unique names and for every entry of a franchise. And if you don't want to number them, at the very least do what Rage of Bahamut did and name everything 'Rage of Bahamut: Some fucking subtitle here'. I mean I'd prefer you number them, but at least do the bare minimum.