It is remarkable how small tactics can finish games quickly, even where Grandmasters are concerned.
Looking at the recent Chebanenko Rapid Open there were two games between GMs that ended decisively in less than 25 moves. Shirov was on the winning side of both.
I am struck by how easy he made it look to take down these GMs, without really doing anything special. They just miscalculated and Shirov took full advantage with some precise play. The clock is a factor, but I doubt either of his victims were in time trouble when they made their mistakes.
Here Shirov plays an Advance against the French and Black seems to be playing fine up until the 17th move and suddenly one tactical oversight ends the game quickly:
Here Shirov starts off playing a Rossolimo against the Sicilian and then he moves back into Open Sicilian territory with 5.d4!? His opponent responds well, and even starts attacking along the h-file, but when he slips up Shirov pounces.
Such tactical oversights are extremely difficult to completely avoid. You would have to literally check-every-move (CEM) your opponent can make at every turn, and that is just not possible with time constraints as they are with tournament play. To help mitigate the risk, you can develop an intuition for when it is a good idea to use CEM, and only adopt it when the position demands it. For example, in highly tactical positions or critical moments. There are routine moves, and there are moves where accuracy is important and getting it right could effect the outcome of a game. Spending more time considering your alternatives at these key moments is justified. I guess in the case of these games, these GMs’ needed to do more checking at certain moves, but unfortunately for them, they didn’t. Hats off to Shirov for demonstrating the flaws in their plans so clinically.