Because of deceleration and loads moving to the outside front your entry speed is limited by the gripping ability of the outside front tire. Once in a corner and prior to full acceleration, there is an opportunity to roll or maintain entry momentum plus additional speed, above entry speed. The driver skill required is to realize once corner entry is completed, transferred weight to the outside will be distributed more evenly between both outside tires, reducing the load on the outside front tire. It provides the opportunity for the driver to slightly increase their rolling corner speed above entry speed and maintain it over a distance. It’s an obvious thing to do, but a tough skill for a driver to learn. Most any corner will provide the opportunity for some additional rolling of the corner at a speed beyond entry. The point is the distance traveled at the enhanced speed of entry momentum plus some acceleration, which is only possible because of grip re-distribution after entry, can be taken in less time, then attempting to accelerate or maintain entry speed over the same distance. How much the advantage will be depends on the turn configuration and the drivers choice in driving line.
It takes specific input and skill by a driver to enter, know when grip redistributes, slightly increase speed, roll with the increases speed and then lead into turn exit and full acceleration. The portion of the turn which can be rolled at increased speed will be taken quicker then if only maintaining entry speed or if trying to accelerate too early, through the same part of the turn.
Yes this is an obvious thing we see happen every day at the races and it’s just one of those obvious not much thought about things. But I think if you think about it a little and compare in your memory good and not so good drivers. I think your memory will be seeing more skilled drivers doing more of it and it’s just one of those un named picture things of higher quality in your mind. We see it every day when watching a skilled driver on the track and I’m now describing a point of why one driver appears to just be better.
ps… I have to add, how much you are able to relate to what I described, also depends on the available hp of what your use to watching out on the track. In general you will see it show more with higher hp. It is because with higher available hp, you will more likely be running closer to the limit of grip.