I special education (ESE) they retest every three years but not full batteries of testing that is done at the beginning of placement. It is retesting only in the areas where people need updated data so if writing is the biggest concern then the focus of retesting would be writing (and anything associated with writing that might help with future planning, OT eval, VMI testing, etc.)and not, say math. You might look at scores from testing that is done on every kid (like the yearly NCBL testing) in all areas but not individual testing in all areas. And for repeat IQ testing there needs to be a reason for it.
In gifted education, I suppose you could apply the same rules to re-evaluation but I don't know if they do or not. Gather what data already exists from group testing, talent search testing, etc. and then determine what areas you need more information and only test in those areas. You don't need a repeated IQ every two years. Some organizations might want a repeated IQ for children who were tested as young preschoolers not using the WISC or SB.
