Subtle differences in the character of the ridge and or location of the TPV can make fairly large differences in outcome. They interact. Waves in the atmosphere behave much like waves in the ocean, so if that amplified ridge 'leans' forward or breaks over, it will result in a deeper, more westward dig of the NS energy.
The other critical aspect is timing. Again, without a block, the Rossby waves are constantly propagating (progressing), so getting the waves of interest to time up the way we need is more difficult.