What do you mean by 'off the spot'?
Dual angles are complex. A person needs to take into consideration the ball's characteristics, the lane pattern, the bowler's speed, RPM's, axis tilt and axis rotation.
Too many bowlers expect too much from minor changes in dual angles. First, drilling only represents 15% or less of a balls reaction. Probably, much less. Rather than thinking of angle combinations, try to think about what the angles will accomplish on the pattern you shoot on. The objective is to have the most speed and RPM's coming off the pattern as your delivery can provide.
Here's an example; When bowlers want back-end, they immediately think they need a shorter pin-to-PAP with an acute VAL angle. This might work but the ball will more than likely lose too much speed and RPM's creating all that motion. On the other hand, by selecting a weaker ball surface, using a narrow drilling angle, a wider pin-to-PAP and a wider VAL angle, the bowler will preserve more speed and RPM's as the ball comes off the pattern resulting in much more hitting power versus just ball motion.
It's really unimportant how much ball motion is created if on impact the ball deflects right of the 9 pin. The objective needs to be where the ball goes off the pin-deck, not from where the ball comes from to hit the pocket.
Only people with 350-450 RPM's can consistently carry those hits with high entry angles. The rest of us are limited to 4-5.5 degrees.