Bleached Lightning
Part 1 of the Bleached Report, Weekly Commentary on the Bleach Anime
39 episodes.
If it maintains its current pace, that's how long I think the Bleach anime adaptation will run.
The first two episodes covered five and four chapters' worth of content; roughly an entire collected volume, which is usually 10 chapters. The final arc of the manga is 20 volumes long and with current trends in anime season length, it stands to reason that this adaptation will probably be broken into three 13-episode cours (This is supported by the material "spoiled" by the opening).
The length and pacing of a manga-to-anime adaptation depend on a variety of factors, including popularity, budget, schedule availability, and the pacing of the manga itself. Bleach itself is an interesting and challenging series to adapt because the amount of content varies so drastically between chapters. Kubo is a master of adjusting the pacing and density of the story in order to modulate the tension throughout an arc and the old industry standard of "two or three chapters per episode" doesn't necessarily apply.
While I already see fans complaining about some of the material that's been cut so far, it also underscores a fundamental difference between mediums:
Unlike manga, where how the author uses their allotted pages is generally up to their discretion, anime has non-negotiable breaks for commercials. This means that you not only have to tell a certain amount of story within the episode but also have to pace and organize it in a way that conforms to these breaks. This usually leads to filler material in order to pad parts of the episode, but given that this current adaptation is running almost a decade after Bleach's serialization ended, that would be impractical and somewhat outrageous to just needlessly extend scenes the way an adaptation of a currently-serialized series would.
Instead, because we have a set number of chapters to work from and a set number of timeslots for airing episodes, material has to be cut for the sake of effectively telling the story in the amount of time provided. This is, sadly, one of the trade-offs for anime being both art and a commodity.
Personally, I prefer the approach that Bleach is taking, which is similar to the one we've seen with Jojo's Bizarre Adventure: Cut the inconsequential and maximize the impact of the material that matters. Even mangaka on strict deadlines will include filler material, often using it to seed ideas that can be used later in a pinch and if a thread goes nowhere, then why include it?