Do you mean that we do not say Good Achis or Good Asik if the thing we want to bring down or up is more than three Tefachim from the ground, as in Sukah 16a? If so this is only a rule in Mechitzos because more than three remains a Mechitzah Teluyah even if we were to say Good Achis (ibid.)

Or do you mean that we do not lower a thing more than three Tefachim with Good Achis as we find in Eiruvin 9a with regards to the rule of Chavot Rami? If so see Tosfos there (Eiruvin 9a DH she'Ein) that in fact we can say Chavot even for more than three, and that Gemara is a special case as we need to use the rule of Lavud as well.

If this does not help, please let me know.

Dov Freedman