getting the speed under control as the first thing you do so that you don't waste energy
If you need to "make it to shore" or "make it over the mountains", yes.
However, I would rather make it with certainty to a closer adequate landing area, than maybe not make it to the [better] more distant landing area, and risk a total crash short of it, because I could not stretch the glide - started by fixating on the glide speed. Thus, making the spot will be the first thing I focus on - right to close final, with speed control erring to too fast/high until the bitter end.
You can always dump speed at the end. Most planes can be slipped right onto the surface with full pedal (the Super Cub on skis did have to be straightened out before touchdown. Drag increases as a square of the speed, so if you have too much speed, the drag you create to rid yourself of the speed will be even more effective. I can always get rid of at least some of too much glide approach speed/altitude, but I cannot recreate it once surrendered!
At the end, (pun intended) I'd rather misjudge, so as to off the far end of the landing spot at 20MPH and dent the plane, than to stall short into the stone wall at 60MPH, and destroy myself and the plane!
When I'm water flying, "best glide speed" will be out the window, unless I'm over forest or ragged mountains. The speed at which greatest distance of altitude lost is achieved, is somewhat more slow than the speed from which a safe power off water landing can be made. If you come into the flare in a seaplane at the "best glide speed", you're in for a very bad splash!