You have to answer a few questions in your own mind in real time:
Is the situation critical -- does it endanger the airplane or those aboard?
Are the conditions such that you can make a successful landing, rollout, and stop?
Is the current inflight situation more dangerous than the IMMEDIATE risks of overweight landing?
Any 2 YES answers likely dictate an overweight landing. You will then have to evaluate whether the risk of the X hours burning fuel is less than the risk of the overweight landing.
Most of these will be subjective, except landing distance on a dry runway...