Same here. I used to leave ongoing ones on I'm Reading even after reading the whole ass 100+ chapters... This was a wrong move on my part because in the end I have no idea if I have read it or not. So now I put the ones I already read complete or ongoing to Already Read and put notes and summary of last chapter read. I'd rather do this than not having any idea if I've read something or not and then fcking up wasting time re reading I still have many I've read on my I'm Reading list but I'm not in the mood to dig atm.
All in all. It's my lists so I don’t really care if others find my lists inconvenient for them since it's my personal page no offense
i notice a lot of people put series on their "already read" list but its always stuff thats just released and still ongoing and i dont get it? i only mark something as already read if the series is completed and im done reading it, with the exception that sometimes a series status changes back to ongoing, or i finished reading it on another site and its just not updated on here yet