When we play off the catch we naturally rip through to attack the rim. But if our left foot is our pivot foot and we rip through to the right, most of the time we are actually traveling.
Now, whether or not it gets called is a different story. But if you shuffle your feet, it is likely to be called a travel.
If you are reading a hard closeout where your defender is leaning and off-balance, utilizing a "Split Catch" is a great way to not only get downhill quicker, but it allows you to not establish a pivot foot. This turns a rip through into a cross step.
Check out this breakdown: