I actually play either 2 or 3 DS at a time. Rarely 4 DS.
In another post I listed the 10 pairs of opposing EC's that can be formed with 3 DS. I have noticed that Dans's observation is largely true for all of them.
A similar observation can be made about the !5 possible "Dozens" that can be made with DS.
Both of these anomalies can be exploited. Remember that such variations are common in the "short term". Over time they tend to cancel each other out. That doesn't stop us taking advantage Of both swings as they occur.
"It don´t mean a thing if it aint got that swing"
Too many people play too many DS at the same time.
Dozens: I have never ever seen a Permanenz without any Dozen series. The most rare dozen tonight may appear only approx. 1/4 of tonight´s spin. Most dozen series consists of exactly TWO spins; and of course the probability of seeing both DS in such a small series is exactly 0.5.
Longer sequences appear from time to time; and then both DS are performing in most series.
"Dozens": I once read, that certain DS pairs have many of its numbers concentrated in certain parts of the European wheel: 1-6 & 19-24.
7-12 & 25-30.
13-18 & 31-36.
The chance of NO STRAIGHT UP REPEAT WITHIN ANY EVEN CHANCE SERIES OF A CERTAIN LENGHT:
Imagine that red appears twice in a row. The probability that the earliest number does not come in the second spin of the series = 17/18.
Within a series of THREE spins the chance of no plein repeat is accordingly (17/18) X (16/18).
And so forth and so on.
According to my cheap calculator the probability of AT LEAST ONE REPEAT
of some number or other within a RED SERIES (for example)
WITH AT LEAST SIX SPINS = Aproxx 60%!