Way back in the 20th century before the Florida Unified Building Code most
local AHJs wanted to see cables sleeved in EMT if the 1.25" could not be
maintained in any dimension. Now they are OK if the cable is secured 1.25"
horizontally from the furring strip, even if the void (to the block) is only
3/4" deep. It is fairly unlikely that a sheetrock installer will miss by that
far but a homeowner will just start driving nails when they hang pictures and
such.