Does trendline work?

That is a very straightforward question.

Answer is
YES AND NO.

do note that the market moves in various manner/shape/fashion .....

 

lol, nice trend. makn bank?

 

I think the trendline can work but also possible to break the line, usually, the trendline is marked support or resistance level zone, if break the line probably will reverse.

 

How would a retest of a disrespected trendline factor in to your view?

 

I think two or three times retest
strong support resistance will make price bounce

 

Of course trendlines work.
Trendlines just represent a good guess where the consensus of traders on the opposite side of a trade may change their mind. And since most traders think in terms of percentage gain (and not total dollar gain), logrithmic charts work better than arithmetic charts.