I have found that the magic percentage to target per day , is 3.5% increase on bank per day.
No more than this.

If one has the ability to do that every day, thats approx 25% increase on bank per week.

Useing the Fibonacci compounding rule of 72
That means the bank would double every 2.88weeks.
72 divided by 25 = 2.88

It can be easily done with the right stratergy.
e.g. Dutching multiple horses and using a well thought out staking plan.

The secret is having the discepline to stop once the percentage is reached.

What generally happens, is that a punter finds himself reaching the 3.5% fairly easy , then says to himself , "lets go again".

For some reason , it starts to get harder & harder to get the next 3.5%
until its all given back & some.

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Cheers.