at the same time, if you really want to keep your instructors ticket ( and i know some who do )then since you cannot revalidate by proficiency ( here we can only do that every second renewal...irrespective of how many hours instructing we have done ) you could simply apply for a flight test each time you want to renew. its an expensive way of doing it but i depends on how badly you want to keep the ticket.
do'nt forget that you still need to do the seminar as well....
good luck...
the dean.