I think it is the story. There is hardly any sub plots and extra character. No copy cat killer on Who & Why or fake tip or an anti OYJ W stalker fan (beside the professor, scene stealer pro), only plot twisting. OYJ's blind date last less than a minute. The webtoon editors appears for like a total of 2 mins. The two girl artists never returns. OYJ's mom probably have a total of less than 5 mins of screen time. OYJ does like 2-3 mins of doctor stuff and KC has 2-3 short fight scenes. Barely any love triangle drama with Soo Hee.

Location is pretty much the same studio, hospital, KC's hotel, inside that K5 product placement car, congressman office, prison, court, MBC station, random motel, random warehouse, and random bus stop.

Also KC probably appears in 70-80% of all of OYJ screen time and she was in fangirl mode until the dream memory wipe.

The CG and artists to draw the webtoon panels probably ate a lot of the budget. Each episode was about 50mins long since they spend 5 mins recapping.