On the other hand, I have my gun checkered underneath the trigger guard. This help secure the index finger of my support hand against the trigger guard. I have a hard chrome frame, without the checkering it's way to slick.
At one time most of the big name shooters in IPSC used the off hand "trigger" finger on the front of the trigger guard. It became kind of a fad and almost every shooter wanted the checkering. Pistols had the knurlling on the trigger guards, re-formed trigger guards (flattened) and were welded up at the bottom of the TG to provide finger grooves. Most of those "improvements" made it rather hard to find holsters that would work for CCW or LEO duty.
Fads change and the number of shooters using that hold have dwindled and the need for TG checkering with them.
------------------ Ne Conjuge Nobiscum MOLON LABE
Leonidas c 480 BC FFF