Here's a look at the gaps left between the common fractional alignments.
The solid lines show where the CB must be in order to make the shot exactly into the center of the pocket (ignoring throw). The dashed lines on either side of each solid line show how far off the solid line the CB (at its base) can be and still make the shot with the same alignment (because the pocket is larger than the OB - in this case 4.5" corner pockets on a 9-foot table).
As you can see, many more shots fall between the "system alignments" than fall on them. These are the "geometric gaps" for this system.
Cookie, I assume you're asking about CTE. The reason nobody can define exactly the geometric gaps for CTE is that CTE has never clearly defined any system alignments. It names the same fractional points on the OB, but how they're used is always described mysteriously as "acquiring the visual" (which you learn to recognize through "experience"). That doesn't mean there aren't gaps, just that CTE isn't described clearly enough to define them.
pj
chgo
Bumped for second considerations as it seems that it's being ignored.
Good diagram Patrick.
Best 2 All,
Rick