While grading away from the house will aid in keeping most surface water from flowing towards the foundation. It will do little to stop ground water infiltration when the soil gets saturated from heavy rains or snow melt. There are some buildings where the grading cannot be raised any further, either because is already at the top of foundation or being at a lower elevation then neighbouring properties. Also excess weight against the foundation wall should be considered, as this can contribute to cracks and bowing in of the foundation.
In short; if you have had a basement leak in the past, then it will require excavation to the base of footing and repaired properly to guarantee it will not reoccur again.