Human + machine assisted tooling is probably going to be the clear winner for a while when it comes to doing quality translations. As far as fully automated goes, I think it depends on language, but for Japanese it's like 80% there.
2 - 4 Translation
1 - 2 Editing
1 - 4 Cleaning
1 - 2 Typesetting
1 Quality Control
The effort involved in cleaning entirely depends on how good the source material is - you'd think professionals would get pristine high resolution pages without text on them, but you'd be wrong. A high quality cleaning job often means repainting a bunch of the art from scratch. If the cleaning is done poorly the typesetter is screwed.
Some stuff is just plain easy to translate, other works will have a single page full of things you have to look up and sentences that only make sense with previous chapters as context (or even worse, FUTURE chapters as context). In some cases translators also have to first transcribe the work because they're sent blurry jpegs or png files instead of being sent text (again, you'd think this wouldn't happen, but...)
QC and editing can often be done by the same person. One subtle gotcha is that your editor or QC (ideally both, but at least one) REALLY need to know the source language even if they're deferring to the translator - if only one of you is able to check the A->B it becomes very hard to spot subtle problems that can mess up the work.