This argument is pretty null. Unless you're going for more obscure sources. Most of the major manga have full translations. We're talking bout manga, not light novels or Visual Novels.
You're not going to have a problem finding full series from Shounen Jump, Shounen Weekly, Ultra Jump, Cheese! or Shojo Beat. Add they're generally collected and unless you're talking about some esoteric series like Shaman King (Which had to jump between 7 different publishers), basically all the relevant material is packaged together.
The way you're talking, I'd think you were talking about a series from Type Moon or Nitro Plus, which aren't manga products. And not manga like one piece or Dragon Ball which are comically easy to pick up and go through