AFAIK (or recollect), secondary security checks only for UK or US flights. (Higher risk level = higher security level)
Of course, if they're departing from an area shared by other gates (UK flights from the dungeons in B Concourse for remote position departures, frinstance), then everyone gets the benefit.
To be honest, it's never bothered me.
The security people aren't as aggressively obnoxious (or as cerebrally challenged) as their UK or US counterparts, the process works smoothly, never missed a flight yet