Slide the slider all the way back just before the optimization starts to disintegrate.
Rule of thumb is to make sure the optimization is fully converged (connected, no disintegration).
Notice the mass of the solution decrease as you slide back.
This however does not mean that the results are necessarily the "optimal" solution.
Run analysis on it and check the animation as well as max displacement etc for a cursory sanity check.
Remember, crap in = crap out, so the more quality information (realistic load cases, model not over constrained etc.) the more likely you are to get optimal results.