SSD
I can't remember having any more than two engines in reheat at once, there was no chance of the aircraft moving as the main gear was trapped between a set of chocks, the rear chocks were concreted into the ground and the front chocks were attached to the rear ones with a set of what looked like surplus battleship anchor chains.
I was always surprised that the pointer on the fuel flow gauge did not respond to the selection of reheat with its own little supersonic shock wave it moved that fast.