Just somethings to be aware of..

1. Usually the tote fluctuations are corrections to the odds of some runners compared to bookies odds. In other words, people see that 10/1 is offered by the bookies but 15/1 available on the tote. They start putting cash on the tote and it's price firms from 15/1 to 10/1.

Guess what happens next?

Tote punters see the price firm from 15/1 into 10/1 and think someone knows something and start backing it until it ends up 7/1 or worse.
All value is lost.

2. Any true plunges normally do not happen on the tote - if someone wants to have a real go at something it happens with the bookies or IASBET etc.

3. Nobody knows when the difference in price between the bookies and tote is a plunge or merely a wrong price assessment by the tote punters. Often bookies will lay a horse (usually favourite) and firm in the price of something else they think has a better chance of upsetting. So it's not really a plunge at all.

4. Plunges come off probably one in five. Even the best information can't be right all the time or the bookies would go broke.

Just some ideas that may not have been factored in. Hope it helps.

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Treat your selection and staking methods not with optimism, nor with pessimism, but with realism.