Hey George, I can just hear it now.

"Honey, I need to get the resonant frequency a few kilohertz higher. Would you go outside and pull off another sheet of siding?!" [Linked Image]

On a more serious note, aluminum siding on houses is extremely rare over here, but a similar situation arises with mobile homes (or "caravans" as they are called here). We are required to bond the structural metalwork to the electrical ground, but not the individual sheets making the outside walls. As has been stated above, to securely bond every piece would require paint to be cleared and/or separate bonding to each sheet.