WTF is wrong with you?...
On average, the target (e.g. the success) is at 50% of the search space (e.g. when half of the maximum work was done). The search space is at 100% of itself.
77% success with 46% effort is a disaster, since you'd only need to scan 38.5% (on average), not 46%.
You think it's better, good for you, what more can I say

Note: all of this is applicable to a non-parallel search. In a full parallel search, X% search = X% success, since all work is performed in parallel (example: all keys are checked at the same time).
I already proved to you that "parallelizing" your prefix method reaches this exact same conclusion. But it's the exact same conclusion to be reached when parallelizing the sequential method. And it's also why the prefix method cannot be parallelized.
Doing combined (parallel sequential sub-searches) can only ever, at most, converge to the serial optimum, which is, again, the average of the searched space, which is, by mathematical definition of averages, at the middle of the amount of searched space.
However, the sequential method CAN be parallelized, because there is no dependency between the sub-regions to scan. With the prefix method, the dependency makes it impossible to parallelize:
FOR block IN blocks:
FOR key IN block:
IF someCondition:
GOTO other block
Should we ask Knuth if this can be run in parallel? It's common knowledge for any CS student, no matter how many times you call it an "engineering challenge", lol.
Tautologies and truisms are not breaking discoveries.