"The increase in volatility is extremely common at market tops and a warning bell is in play after the parabolic type moves at the end of the market cycle." The academic evidence tends to disagree. In their April 2017 paper entitled “Can We Use Volatility to Diagnose Financial Bubbles? Lessons from 40 Historical Bubbles”, Didier Sornette, Peter Cauwels and Georgi Smilyanov examine price volatility before, during, and after financial asset bubbles in order to uncover possible commonalities and check empirically whether volatility might be used as an indicator or an early warning signal of an unsustainable price increase and the associated crash. Somewhat contrary to previous academic and practitioner claims, the main finding of this paper is that there is no systematic evidence of increasing volatility as a diagnostic or an early warning signal that a bubble is present and or developing. Sometimes volatility does tend to increase, other times it decreases before a fall, and most of the time volatility barely changes as the bubble develops towards its end.
The turn of the month effect is not just a November anomaly. http://www.cfainstitute.org/learning/products/publications/faj/Pages/faj.v64.n2.11.aspx
After taking out the 2 maximum gains (1997 gain 10.59%, 2008 gain 11.08%) the data still passes muster producing an average 5-day return of 1.03% with statistical significance at north of the 1 in 10 level.
The return of 2.17% for the 20-day forward interval is over 4 times that of the average 20-day return for the All Ordinaries Index from 1990 to 2013 of 0.45%. Also, your conditional win rate of 90% is significantly higher than that of any random 20-day interval of 59%.
The return of 2.92% for the 15-day forward interval is 6 times that of the average 15-day return from 1990 to 2013 of 0.48%.