allout-doublecheck-at-and-shallower is a variable defined in `allout.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

Validate apparent topics of this depth and shallower as being non-aberrant.

Verified with `allout-aberrant-container-p'. The usefulness of
this check is limited to shallow depths, because the
determination of aberrance is according to the mistaken item
being followed by a legitimate item of excessively greater depth.

The classic example of a mistaken item, for a standard allout
outline configuration, is a body line that begins with an '...'
ellipsis. This happens to contain a legitimate depth-2 header
prefix, constituted by two '..' dots at the beginning of the
line. The only thing that can distinguish it *in principle* from
a legitimate one is if the following real header is at a depth
that is discontinuous from the depth of 2 implied by the
ellipsis, ie depth 4 or more. As the depth being tested gets
greater, the likelihood of this kind of disqualification is
lower, and the usefulness of this test is lower.

Extending the depth of the doublecheck increases the amount it is
applied, increasing the cost of the test - on casual estimation,
for outlines with many deep topics, geometrically (O(n)?).
Taken together with decreasing likelihood that the test will be
useful at greater depths, more modest doublecheck limits are more
suitably economical.