Hayward generally gives a range of 2700-3400 ppm. However, there are consequences for running at too high or too low of a salt level. In both cases, the unit can shut off. At the high end, these units will shut off at 8 amps which is dependent on both salt level and water temperature. On the low end the units will start to warn you at 2600 ppm of low salt and then shut off at 2400 ppm or below.
However a word of caution, at the high end of the range, current gets higher and more heat is generated in the SWG unit which can cause premature failure, a not so rare problem with Hayward SWGs. So I tend to keep my salt level closer to the lower range (~2900 ppm). This is lower than Haywards suggestion of 3200 ppm but as I said before, it helps prevent board failures. Also, there is no real downside to keeping salt levels on the lower end of the range other than slightly lower CL production which can easily be compensated for by a higher percent setting.
But in general, if the SWG unit does not complain, then I would not get overly concerned about salt level. When the unit alarms with a low salt level, it is a good idea to get an independent test to confirm. Salt cells will typical register low salt levels when they begin to fail. You don't want to add salt to a pool when it is already high enough and then after replacing the cell, the salt level is then too high for the new cell and partial drain is required.