I found the following tactical elements:
- Double attack
- Discovered attack
- Hanging piece
This opens up a whole area of preliminary moves between positional moves and the actual execution of a tactical element.
The goal of a positional move is to diminish the posibilities of the opponent relatively to your own possibilities. The goal is to limit the possibilities of your opponent to such extend that he can no longer meet your threats. When that moment arises, you can execute a tactical element.
There are the typical positional moves like gaining space, get an outpost, occupy an open line etc. to work on the relative possibilities of the two sides. But between a positional move and the final execution of a tactical element, a whole area of prelimanary tactical moves submerges.
The problems of CT are derived from real games. If a problem contains 6-10 tactical elements what does that mean? It means that the player during the game has put 6-10 tactical elements into place. That doesn't happen overnight. There are at least 6-10 moves necessary to install these tactical elements. Probably more.
Every tactical element does need one or more defenders to prevent it from execution. This means that the possibilities of the opponent are greatly diminished by binding defenders to tactical elements. When there are 6-10 tactical elements, there are at least 6-10 defenders needed to prevent them from execution. A winning combination prevails once all important defenders are bound and you can pose a threat that cannot be met. That are the kind of problems CT is presenting us.
In practical play, the amount of tactical elements that is needed may vary greatly. One defender can defend against one or more threats. When a defender defends against more than one threat, that might mean that the defender is overworked. The execution of a tactical element starts when the opponent has run out of defenders. A cramped position on the board (or a blunder) might cause that on a certain part of the board your opponent runs out of defenders rather soon. In case of an overworked piece, you execute one of the threats, thus decoying the defender from the other threat(s) he was defending. Bottomline is that the execution of a combination starts when there is at least one tactical element without defender.