Stretching the glide
Regarding BA 38:
Initially it was the AP that attempted to "stretch the glide" - trying to hold the glideslope without enough power. Which resulted in a classic airspeed decay. The pilots didn't have much to work with by the time they took control at 108 kts.
In a micro-sense, one may be able to trade a little speed for a little distance or height at the last moment - enough to make a difference clearing a hedge, ditch, 8-foot antenna or a car on a roadway. But BA 38 didn't make the runway, and touched down stalled, with no control authority for the FO to make a flare (although he tried). Fortunately, soft soil and the snapping of the gear cushioned the impact just enough for the souls on board.
In the present accident, sadly, that minor amount of last-minute control would, from the pix, only have allowed a choice of which floor of the building the plane would hit.
If one is above best glide speed at the instant of power failure (or any point thereafter), one can gain some glide range by immediately pulling the nose up to reduce speed to the best glide speed.