What is omitted between 'the task' and 'and'?

Question

What is omitted between the more tasks and and? 'the to-do lists had'?

The results in the Journal of Experimental Psychology confirm that not all pre-sleep writing is created equal. Those who’d made to-do lists before bed were able to fall asleep nine minutes faster than the ones who’d written about past events. The quality of the lists mattered, too; the more tasks and the more specific the to-do lists were, the faster the writers fell asleep. On the flip side, those who wrote long lists of accomplishments took longer to fall asleep than those who’d thought of fewer past activities.

[Source : This 5-Minute Bedtime Ritual Will Make You Fall Asleep Faster] (https://www.rd.com/health/wellness/mind-racing-sleep-trick/)

Answer 1

First of all, there's nothing actually ungrammatical about the sentence as it stands. However, stylistically, it doesn't flow very well.

There are a couple of way of making the sentence sound more natural; all of them involve forming a more clearly parallel structure to the sentence.

The form I prefer is the following:

The ^{A the B} and ^{the C the D}, the X the Y.

In other words, rephrase the first item in the example sentence and remove were from the second item:

✔ The quality of the lists mattered, too; ^{the greater the number of tasks} and ^{the more specific the to-do lists}, the faster the writers fell asleep.

However, this is stylistic rather than grammatical.

---

You could also get away with simply adding there were to the first item. While this directly answers the question in terms of adding something, I think it would also sound a bit repetitive and not as natural as the first suggestion.

The quality of the lists mattered, too; ^{the more tasks there were} and ^{the more specific the to-do lists were}, the faster the writers fell asleep.

Answer 2

The quality of the lists mattered, too; the more tasks and the more specific the to-do lists were, the faster the writers fell asleep

What is missing is a past participle, such as "listed" or "included", but this is not the main problem. One issue is that the number of tasks is a quantitative measure, and not an example of how the quality of the lists mattered. Another issue is that without more information it is unclear whether it was important for the lists to include many tasks, specific tasks, or many specific tasks. It is also awkward that the the first example refers to the tasks while the second example refers to the list itself. The authors could have written "the more tasks listed, and the more specific they were..." but this too is awkward. Here is a more direct way to express the same idea: "Writers who produced longer lists of specific tasks fell asleep faster than those who produced shorter lists of nebulous tasks."