Exactly. It's about energy management not speed or height per se.
In my type (B757 - and I'm sure it's similar for most jet transports) in a normal descent (circa .79/290 knots) three times my current FL (minus the last zero) + 10 miles to slow down (to clean speed) gives all I need for descent planning (based on no speedbrake/early gear etc.). Beware overcomplicating. The FMC vertical profile (if programmed with what you expect/want to do correctly) is a good backup/cross-check and esp. useful in a managed approach.
Assuming an airfield close to sea level...
If I'm at 250 knots and at FL120 I'll look for (12 x 3) + 5 miles (if I was 300 knots, it would be + 10 miles, if I was 240 knots it would be + 4 miles, etc.) to slow down i.e. 41 miles. If the FMC says 60 miles until touchdown (and the FMC has been updated during descent to reflect the likely reality) I'm low (on energy) and will shallow off the descent/speed up etc. If it says 25 miles until touchdown I'm high (on energy i.e. speed/height) and will probably use some speedbrake to improve things.
It's all about doing a quick calculation (based on the above) at several points during the descent and reacting accordingly...in my humble, and still limited, experience!
Seems to work well. In the latterstages of the approach you'll have glideslope/DME/the picture out of the window to tweak it a bit.
You'll fluff it some of the time though due to ATC doing unforeseen things or you just miscalculating!
Shizzle happens...
Hope this helps?
B&S