Windows positioning with applescript
Use the modulo operator ! 

set Auch to {...}      --list with all windows
set positionArray to {{..}, {..},{..}} -- The array where you store the positions you want. 

set ind to 0
repeat with theWindow in Auch
    tell (windows whose title contains theWindow)
        activate
        set position to item ((ind mod (count of positionArray)) + 1) of positionArray --AppleScript arrays start at 1 
        set ind to (ind + 1)
    end tell
end repeat