What's the tailwind component? What's the headwind component? If you're at 190 kts and it's 60 kts it's either 130 Kts GS or 250 kts GS.
IMO it's a waste of time remembering those values and I like ball park data. But the example above show it could be .7x, x, or 1.3x.(x=GS) for a given ROD.
IMO look outside and evaluate distance to go vs altitude to lose. FMC, VTI, or green arc, are excellent tools. Are you regaining your desired profile in time? Yes = stick with what you got. No? How far off of profile? How much distance is left to regain profile? Make the smallest adjustment(speedbrakes, more flaps or gear) consistent with regaining profile.
I was just going to assume it was in still air for the time being.
Don't get me wrong I'm not intending to use these values in the air - not sure my brain could cope with that!! I'd always do what you suggested above!
I just wanted to gain more understanding into the mathematics behind it - just out of a personal interest. If I'm using those techniques as you mentioned above I would just prefer for me to have a decent grasp on the dynamics/mathematics at play instead of letting myself just doing it because it worked...if that makes sense?