I have played MediaCenter for over 1000 days (1000 * 24 hours)...since MJ8. My system simply counts the track duration of all in my library * the number plays. This last year I started tracking deleted tracks and that time too... I believe I have got my money's worth.
MediaCenter Music Album List Monday 2016-05-02 19:30:09
Artists: 932 Owned: 48:18:29 Unrated: 268 1.8%
Albums: 3,139 Played: 1000:04:59 Rating2: 207 1.4%
Tracks: 14,786 Never: 1:00:29 Rating3: 8,274 56.0%
Skipped: 1 YTD: 46:19:09 Rating4: 3,780 25.6%
Hours/Day: 9.15 MTD: 0:13:52 Rating5: 2,256 15.3%
Deleted: 50:23:21 Lossy: 1,614 10.9%