So much about serving the needs of the tails (at either end, let alone when both tails are present in the same individual) is about least-worst solutions.
In my ideal educational world (which might not be yours, of course!), I would de-couple academic instructional levels from age, and from the levels of the other subjects, scaffolding for essential cross-domain skills when necessary to provide access to the ZPD in areas of strength, and targeting areas of weakness for intensive remediation.
But then, that's why we homeschool.
I am aware that the level of respect for individual learning and developmental needs I envision is extremely difficult to implement practically and with fidelity in our current industrialized education model, which, after all, was built for the middle 68% (and in a different era). Patches have been legislated for the lower 16%, with variable levels of success. (Some slow progress has been made on the left tail, in terms of aspects of equity and inclusion.) The right hand 16% continues to struggle for acknowledgement as a part of the natural diversity of the human population--with the same equity, diversity and inclusion rights as any other subgroup--rather than assignment to a privileged, resource-hoarding social class.
And the additional challenge, of course, is that there -is- overlap, not insubstantial, in who actually ends up with access to instructional programming appropriate to the upper 16.
There are many dimensions to equity in education; when resources are limited, any method of selection will result in some type of inequity. We choose only which type we will tolerate. The true tragedy is that our systems have allowed this severity of resource scarcity to persist for generations.
