I'm mining Seren Stones, and it's constantly taking more than 15 seconds, because of my low mining level, to get XP from it. If we had a larger range, say 1 minute or so, on the AFK timer attached to the XP Meter, it would be much appreciated.
Check out this thread.
The reason that it isn't longer than 15 sec right now is because it is kind of useless to alert after so much time. But the afkwarden app has some other ways to detect that you're no longer mining.