…I really think it should be included in the Rules section...
Adding "jump on seeding" as a rule is really a tough situation. Why you ask?
Scenario 1:
What if an uploader is just sharing something I uploaded to another torrent tracker and I happen to come across it here on GTRU. I did all the hard work of creating the torrent so why should he/she get all the seeding credit here?
I guess that scenario brings up an equally important question in reverse. Have you ever downloaded anything from another tracker here and shared it elsewhere or, downloaded from another tracker and shared it here?
I will readily admit I'm guilty of both. And I've a good feeling, that isn't such a small club. What I do now is, I'll create two torrents, one for here and one for the other tracker. I launch one on either tracker and, as soon as I have leeches, I launch the second on the other tracker and seed both using the same file. (For the record, I use a seedbox, so speed and output don't pose problems seeding the same file on two torrents.)
Lastly, I said this in another thread. In all honesty, before I even used a seedbox, I used to welcome jump on seeding (for torrents that I launched) as it meant more people got the videos quicker. But that's just my personal opinion.