A lot of people get overzealous with their shoe shining and want to cover the entire toe cap using the cap line as their metric of measurement. The problem with this ideology is pattern making has come a long way since the days of solely very traditional and classic shoes were being made. That means that the cap line is not always the defining indicator of where the toe puff ends. And what that means is that where the toe puff ends is where the leather becomes soft again i.e. susceptible to creasing. And if you shine too much where there is a crease line it becomes vulnerable to cracking. And it looks terrible when a mirror shine cracks. You essentially have to strip it down and start fresh. And that takes a while to do.
So knowing where that line falls (i.e. the toe puff line) is the key to make a good cap shine. As you can see here, @Mr.Renwoks of Instagram knows where that line falls. And you can actually see it as he cleverly finished his shine just where the puff ends, making a lovely gradient of mirror shine at the tips to light shine at the vamp. And that is the perfect cap shine.
Well done to Mr. Renworks.