trade timing signals - using Advance-Decline line tools

[rimshot]

$NYSI daily which also shows that
the $NYA has closed a single day on Friday September 4, 2020
slightly below the $NYA 21-day EMA --

http://stockcharts.com/c-sc/sc?s=%24NYSI&p=D&st=2013-01-01&i=p20160592972&a=382915264&r=1599014267111

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* the chart above displays the $NYSI daily over several years along with the plot
of SPY daily price closes --

* are we going to steadily repeat what took place in 1st half of 2018 &
4th quarter 2018
and
in January to March 2020?
when $NYSI was declining like it has been doing in second half of August and in September 2020 ... in advance
of the SPY price action actually turning down
until many weeks after the $NYSI decline was well underway
for several weeks/months in early 2018 and 3rd/4th quarter 2018 and in early 2020?