I think your, convoluted, example would be better if you hadn&#x27;t merely added in parentheses randomly. Parenthetical and asides are sub-statements, and, typically, can be omitted without losing the overall meaning of the expression.<p>Take my above asides &quot;, convoluted,&quot; and &quot;, typically,&quot;. Neither are necessary for understanding the sentence, but neither make the sentence exceptionally difficult to understand for a literate reader.<p>The method in which parentheses (and other structuring notations) are used is more akin to grouping from algebra and mathematics.<p>EDIT:<p>Original:
OTOH, following something (say, an English text) (which is heavily parenthesised) may be (I&#x27;m sure there is a lot of references to back this notion) exceptionally hard (even if there is just one nested level (and more levels certainly add more confusion)). Choosing flat over structured often makes a lot sense.<p>But it doesn&#x27;t make sense when we remove the parenthetical statements:<p><pre><code>  OTOH, following something may be exceptionally hard.
  Choosing flat over structured often makes a lot [of]
  sense.
</code></pre>
(one edit for clarity). That first sentence has lost all meaning. Following <i>what</i>? Following a car on foot can, indeed, be exceptionally hard. But following a slug is often exceptionally easy.<p>A more reasonable version of your sentence:<p><pre><code>  OTOH, following something--say, an English text--which
  is heavily parenthesised may be, I&#x27;m sure there is a
  lot of references to back this notion, exceptionally
  hard (even if there is just one nested level (and more
  levels certainly add more confusion)). Choosing flat
  over structured often makes a lot sense.
</code></pre>
Now the remaining asides (demarcated using the various English notations of em-dash, comma or parenthesis) can be removed without losing the general sense of your sentence.