Refer to Goertz and Sturgess, Pp 1073-5(green edition); for more discussion.
The original purpose for the grooves, ordered to be added by the Reichswehr, and before and separate from any Mauser involvement- was to allow powder buildup and oil/grease a place to move away from the front of the striker.
The possible, but small improvement in gas venting, mentioned by Vilm, would depend much on how large/long the individual grooves were cut; but, gas venting was not the original or main concern when the grooves were ordered.
A very small percentage of groves that I have observed will reach the sear cut out- but very few.
The observed radial location of the grooves is random. IF gas management was important and the actual/main reason that the grooves were added, the position of said grooves would not be random, but at least one groove would be centered at the sear cut- and made deep/long enough to reach the cut.
Marc is correct that most/much of this discussion is opinion or speculation, especially the speculation that Mauser "tested" the previously ordered and established grooves- Mauser would have had no choice but to continue an approved and ordered design feature. JMHO.
If Georg Luger thought his bolt patent covered the luger pistol striker, I believe we can be sure he(or his heirs) would have insisted or at least tried to be paid for that "improvement". Again JMHO.
I think this horse is well and thoroughly dead now, and I'll stop writing about it.