In the mood to engage in a little free speculation today.
There is a section in the Isshinru Seosan Kata, where you first side block and the double punch, front kick, and deliver and ending punch.
Of many underlying principles the one that comes to the top to me is the Overload Principle. Throwing so many things at an opponent, assuming they have strengthened their body to accept a blow, the many almost simultaneous strikes allow one of them to breach that core protection and end the matter.
One variation might be to begin with the forward foot stepping on their instep. Then delivering those strikes, so when they do go down they also injure that foot in the process.
Another variation might be to move the kick to the end, for a big finish, so they face a 1,2,3 punching pattern then an ending kick.
Of course the action might be performed with a ‘block as press down (Osae)’ or with a ‘block that sucks, pulling them forward’ closer to your response, as well as a ‘block as a opening strike’ and of course a ‘block as a deflection’ Each use of the block creating a different place to move the opponent into for the rest of the response.
In a similar vein you can go forward, or you can move in reverse, or you can shift to the side angles (both sides of the strike) and obtain different answers.
But I reflect on the technique found in another very old Okinawan kata, that of Kata Jion.
I have read speculation that the older method of striking, was to strike to the head, and the strikes to the chest were later changes to striking allowing safer group instruction.
Of course, it is interesting, but I have no idea if that was how it came about. Certainly strikes into the chest work.
But lets play with that idea l little.
The three strikes could be delivered to face, solar plexus then groin. I have these photos of my instructor Tom Lewis doing something like this.