I believe that in order to hit the sweetspot consistently, the ball must be struck with a shallow descending angle.

My point is illustrated in the above pictures of the great Jack Nicklaus. Many people believe that Nicklaus struck the ball on the upswing as his follow-through was higher than his backswing. This is nonsense as the pictures here clearly show. To get from frame 1 to frame 2 there is only one route and that's a descending trajectory. Jack's shaft is also leaning forward at impact, indicating a descending blow.

To improve your strike, lean on the front foot like Jack and focus on a descending blow. I can't guarantee 18 majors but you'll gain better feel and will lower your putting stats.