Overstacking can be very dangerous against an agressive opponent. If a player is not able to get down to the garbage efficiently, he'll be overwhelmed by garbage.
Fundamental
In this situation, a player overstacks and takes longer to get down to the garbage.
With the same sequence of pieces, a player can opt to switch the position of the T and the J, resulting in a clean opening for the garbage.
Towering
When facing an ever changing system of garbage, often, a player has to make the field uneven in height to avoid overstacking.
Be wary when towering because it's not always productive. If a player is not careful, he may end up severely decreasing his options in tetromino placement.
