Is there any reason why chunking the digit span test would not help Is there any reason why chunking the digit span test would not help, and what is the average score without chunking? By chunking I mean any rehearsal besides saying the numbers one time as they appear.

I asked a similar question already:

Does the digit span test draw on any executive functions besides working memory, if &quot;chunking&quot; is not used?

Just intrigued why chunking might not work as well (and it's trivial that it won't always work as well), or not at all.
As far as I know the effectiveness of chunking depends on (1) test speed and (2) amount of practice.

At low speed simple techniquest benefit almost everyone a little, even with virtually no practice. Quoting from Dempster and Zinkgraf


  Recently, in fact, evidence has been found that questions the validity of the assumption
  that chunking plays a role in digit-span variance. In one experiment,
  Lyon (1977) presented 12-item digit sequences to adult subjects for whom conventional
  digit-span estimates were available, and instructed them to think of each
  successive group of three digits as a three-digit number. The important result was
  that subjects with high spans (average = 8.3) benefited just as much from the chunking
  instructions as those with low spans (average = 6.1). Thus, prompting all subjects to
  impose a common structure on the lists did not produce the convergence of the two
  groups that would be expected if chunking was the source of differences between
  subjects in the high- and low-span groups.


On the other hand


  However, it does seem plausible that the temporal characteristics of
  the digit-span task (rapid presentation rate and single trial) simply allow little opportunity
  for chunking, unless the individual is exceptionally adept at creating
  chunks (Hunt &amp; Love, 1972, pp. 248-250), or has received an extended period of
  practice (Ericsson, Chase, &amp; Faloon, 1980; Gates &amp; Taylor, 1925; Martin &amp;
  Fernberger, 1929). For such an individual, chunking can be a highly successful
  strategy. 


The "extended practice" mentioned there involves associative techniques not merely chunking.