Phlap1,
did someone teach you this during training? If so, I would challenge the guy. Energy wise (certainly during a LDA or CDApproach) it is nonsense.
You could however extend flaps at placard speed, but not only does it increases flap/slat wear it is also risky. You might get overspeed (or at least getting the warning) in case of entering unexpected changes in meteo conditions (T, wind).
Can't add much more than what you can read in previous comments.
Another thing people forget is that speedbrakes/spoilers are only effective at higher speeds ( 240kts and more, the higher the better). When you have problems configuring during an approach and you cannot trade thrust or altitude for speed, the most effective speedkiller would be to use the gear.