Grill rule?

No, but don’t pierce the steak with a grill fork, it lets the juices out.
Use tongs (long ones to avoid burning your hands) instead.,

SRM

When you flip a steak, the side that has been grilling loses its temperature very quickly. So when you flip the steak many times, it can take longer to cook. The same principle applies to stirring soups and sauces when you’re cooking. The longer you let it sit untouched, the better (unless it’s so long that it turns black). Also, leaving it alone allows for caramelization (grill marks, burnt toasty bits) to happen, which raises the flavor and texture quotient.

The less you fuss with it, the better. Don’t move it around. Sear nice & brown on one side, then flip and cook until done. Use a meat thermometer. That’s it.

I am a belivers of the one flip steak

I know that it is better to not flip any meat more than once while grilling. That said, the OCD in me forbids me from acting on that knowledge.