Thanks for your question. The idea of syllabus with its contigent notions of selection and sequencing opens up a whole can of worms for teachers. I’ll be very brief here and limit the discussion to English teaching.
When I wrote, “the reason for the failure of an educational programme may the paucity of input”, I had in mind the 50,000 chess positions and what they entail in terms of knowledge to derive any position (i.e. individual piece move, strategies, tactics, and so on) which put together may lead to literally hundreds of thousands of single-item pieces of data. I also had in mind a couple of introductory stats books I have on my shelf which both run to over 700 pages of dense information. Finally, I am aware than in music, there are uncountable (at least informally) numbers of data that need to be processed prior to expert performance.
In EFL, I have the Betty Azar, the Celce-Murcia/Larsen-Freeman, the Quirk and Greenbaum grammar books and a few more. Aside from TOEIC/ TOEFL preparation books, these grammars are the biggest books for English, yet they contain 1/4 the pages of the stats books. Of course, English is not only grammar, but my own informal study of the sytactic structures typically found in textbooks (in Japan) showed that most available textbooks used only a very small subset of that contained in the grammar books, and that most were grammar-based. In fact, I counted (I’ve forgotten the exact number but it was less than) 40 commonly-used structures that were used to teach 126 diffent meanings; i.e. the present simple (counted once) used for: timetables, present narratives, regularly occuring events, use in conditional clauses (4 meanings).
In other words, if we rely on grammar as an input source, we limit the available data to students exponentially. Adding situational, tasks, projects and so on will help increase the input. But I wonder if (for example) our focus on grammar and vocabulary make us miss the greater whole of English data and thereby fail to present students with enough key information.