I started passing insanes at around 2.5-3k plays. Maybe less. I always played maps that were out of my skill level though, so maybe I just took a shortcut per se to get to the harder maps.
Recently I started getting perfect combos on insanes and I got my first 2 S ranks on insanes within the last week with around 5k plays ^_^
However, i'm not too sure about the accuracy of how many plays I actually have, since most of them are just me failing near the beginning many, many times (if you look at my historical) or failing an fc and restarting immediately. So in reality the plays may be less... oh and I'm currently siutting at around 5.8k~ plays.