The slowness of the Made in Abyss manga might be due to the author's meticulous approach. They could be aiming for a more polished and immersive experience for the readers, which takes additional time and effort.
The complex world of 'Made in Abyss' offers a lot of room for fanfiction. The Abyss itself is full of mysteries and the characters are richly developed. Fans are drawn to write fanfiction to explore different theories about the Abyss, like what lies at the very bottom. Also, the relationships between the characters, like the bond between Riko and Reg, give writers a lot to work with.
The unexpectedness of the outcome. Most polls predicted Clinton would win, so when Trump won, it was a huge shock. People were unprepared for such a change.
The answer is yes. Made in Abyss began as a novel. This original form allowed the creator to lay out the core ideas and storylines that were later brought to life in other visual and narrative formats.
The Made in Abyss manga is on hiatus for now. Maybe the author needs time to flesh out the story or there could be other behind-the-scenes factors affecting the schedule.