Working one year ahead probably works best for the mildly gifted, kids with an IQ of about 110 to 130. Which is of course not the top 2% of the cohort, rather the top 25%. Makes for impressive numbers in the gifted program and makes 25% of parents happy. The moderately gifted kids probably do okay as well, but for the HG+ cohort, it's no more than a bandaid.
A program like this would more or less correspond to the high achiever track where I live. The local gifted program (130 or above, but expanded to 120 or above now, though so far it's skewed higher due to most parents preferring high achiever track for their kids) takes the regular high achiever curriculum and telescopes it by year, using about 75% of the time for the regular curriculum, and the rest for enrichment.
