@neorasp thats usualy how the raws/original work is distributed. Instead of getting one chapter a month, and thus buying one manga per month (and possibly forgetting about the work), you get half a chapter every week and a half (or p% of a chapter every n days). If you don't like it, you will have to wait till all parts are uploaded. the number of parts per chapter doesn't usually change, so it should be easy to tell if a chapter is completed or not.
its an incredibly common practice, so its best to be prepared for it.