The lines are drawn taking into account the HIGH points & LOW Points. If the prices are below 61.8% this is considered still bearish and once the share is crossing 61.8% you identify the trend has changed and its BULLISH and people would BUY. with slight pull back on selling off.
Assuming the counter moves towards lets say 190rs then usually what happens is that the initial profit taking do occur that could bring the SAMP back to 170-180 levels if you are a trader.
This will give another opportunity to BUY in further driving the Price go above previous HIGH around 190
for me I will buy few thousands around 170-172 levels with expecting more fall towards 160. where I will accumulate more ....