Wow, listening straight through their discography...that's commitment. I love shuffle play too much to listen to one artist/group for too long.
For me, I’m usually like “I really like this. Now give all of it.”, and that’s why I’ll listen to everything in order. And trust me, that’s not even that crazy for me. I spent a whole day one weekend listening to Umamusume Winning Live! albums. I actually have my timesheet I used to keep track of how long it took laying around, so I’ll get a time estimate here. Looks like I went from 10:00am to 12:00PM, had lunch, came back at 12:30PM, left at 1:20PM, came back 1:45PM, then left again at 2:00PM, came back at 2:30PM, left at 3:45PM, came back at 4:53, went to have dinner at 5:20PM, came back at 6:00PM, left at 7:00PM, came back at 7:40PM, and went until 10:10PM.
TLDR: About 8 hours.