I've wanted to build something like this for a long time, cool (and unsurprising, really) to see it's already done!
Swans is my number 30 by scrobbles but 4 by playtime, which makes total sense.
E.g. Fishmans - Long Season is a 40 minute song, but the website's considers it as divided into 4-5 parts. And you don't have to listen to the full song to get a scrobble.
In the Spotify data you get the exact number of seconds you listened to it. And it is surprisingly complete and easy to use too. With LLMs I bet you can load it into pandas and construct queries for any insight you want in seconds.