Responses
True but think of it this way...because they are making the Parts simultaneously (including Part 5, the beginning of which is posted somewhere else), we'll get to see the ending of the manga faster.
Also, Suzuka-sensei who illustrated Parts1-2 came back to illustrated Part 5
Part 1 - Suzuka (DONE)
Part 2 - Suzuka (DONE)
Part 3 - Ryo Namino (Ongoing)
Part 4 - Hikaru Katsuki (Ongoing)
Part 5 - Suzuka (Started)
It is not complete, far from finished. Apparently, the manga artist only uploads 1 chapter from the current volume once a month or every two months. That is quite slow.
Moreover, the artist of part 4 volume 1 is different. One artist is working on part 3 and the other on 4 at the same time. That is indeed confusing. In my opinion It is best to read the novel of part 3 volume 3. Part 3 has a total of 5 volumes.