Tote odds shortening means nothing despite what the presenters on Sky gush about. Most tote activity occurs in the final 10 minutes of betting and most of the time the shorteners/drifters are simply corrections according to the horses on course price. How often do you hear one of the Sky presenters say " the big money/smart money has come for number 6 Radish - $10 into $6 now. WOW! "
Quite often when examining on course fluctuations (the real indicator of where money is going) Radish probably opened at $5 and drifted to $6 and the punters who saw $10 on the tote with 5 minutes to go crunched it.
As for on course fluctuations, the reason most winners are drifters is that most runners are drifters. The opening prices bet are a joke ( about 150% in most instances)and are there to test the water. Prices generally drift to about 120% without a nibble for anything and then in the last 10 minutes or so the real activity takes place.
With the totes it's also a consideration that some horses, particularly in later races, may open very short because of a big allup bet going into it. As the pool swells most of the money is for the other runners who are over the on course odds because of the shorty. Things usually level out but the illusion to off course punters is that there is some sort of plunge going on.
I have often wondered also how much one bet can circulate in the betting ring. By this I mean if a punter places $10000 on a 5/1 shot, how often is that bet laid off around the ring. One $10000 bet from a keen owner could be bet back a dozen times and give the appearance of a "bit of a go".
My bottom line is, don't let any betting activity influence your thinking.