Because it's about the journey and not the destination. Don't you ever read a slice of life series and wonder what the characters were doing during all the time skips? We are getting a day by day exposition of Kazuya's relationship development with Mizuhara, and while most manga editors would say "No, don't do that. You're crazy" Reiji's editor seems to basically be letting him do what he wants at this point.I mean how else do you have a slice of life romance series go this many chapters without drawing it out like this?
For what it's worth, I don't see people hating on it like this anywhere outside of MD or *chan. The series must be a major cash cow for the publishers for them to let Reiji basically do day by day progress in a slice of life manga. I'm trying to think of something similar that went this long.