The countdowns are a family of patterns in which you constantly change the main pattern. For instance, you start with a 4-count cycle, a 3-count cycle, a 2-count cycle, an ultimate cycle (only one pass) and back, and so on.
As you can guess, the word "countdown" is not completely appropriate, since you count up as much as you count down. The countdown from 3 is the shorter, since a countdown from 2 is a simple PPS. .
We start then from 3-count, hence we do a 3-count cycle, then a 2-count cycle
a 1-count, a 2-count, and then we start again.
This rhythm is a cycle of 8 throws, which means there are two versions of it (one starts with a RH pass, the other with a LH pass). This rhythm is not symetrical, since it has an even number of throws.
The entire sequence is PSSPSPPS, easier to remember when you think of it as PSSP-SPPS.
It's also a practice for the 7 clubs version : Copenhagen countdown
Run a 4-count cycle, a 3-count cycle, a 2-count, a 1-count, a 2-count and
a 3-count, then starts from the other hand. As opposed to the countdown from 3
there is only one version since you alternate a start with the RH and a start in the LH
in the same pattern.
The sequence is PSSSPSSPSPPSPSS, but you'd rather count in your head than learn it by heart.
And it's also a practice for the 7 clubs version : Oslo countdown