It was called ‘overspeed’, and was used in some cases in the 747. Now, the electronic manuals will vary the speeds to maximise any benefit, without you having to specifically choose to do so, or even having any indication that it’s been applied.
I expect that you‘re referring to excess runway as being the black bit that’s left between the end and your lift off point. But, the calculations are more about the abort/go cases. For a balanced field length, the point at which you come to a stop from a V1 abort is calculated to equal the point at which you’d reach 35’ in the go case. Excess runway is any distance beyond that point, so the actual amount of excess is dramatically less than is evident in a normal take off.
There is a performance advantage to be had, as you’re accelerating on the ground, without the induced drag of the airborne wing. The negative is the rolling drag from the undercarriage, which itself, amounts to thousands of pounds in a 747. As best I recall though, the increase in speed to Vr was less than 10 knots.
