What sort of ATC factors would be considered by T5 Stands? From my experience the only consideration would be in a dynamic situation where an inbound aircraft is physically unable to park (due to another aircraft with a technical problem, or a stranded tug etc) on the allocated stand, and that's more of a business imperative (getting pax off the aircraft) rather than anything ATC-led.

T5A has three heavy stands; 518, which is self contained, and 514 and 516 which are part of a multi-use apron, usually configured to have A320 family aircraft on stands 517, 515 and 513, so 514 and 516 are not normally used.