I know this is a very basic question but we only ever trade with our own money so its not something we've ever really thought about.
What do you mean by T+3 dumping?
I know you generally have three days to settle after buying shares but in order to not pay for shares I was under the impression that you had to buy and sell the same day. If you buy one day and sell two days later you still have to pay for the shares, its just that you get the sale credited the next day.
I've been reading the thread about the Bowral guy and he mentions that he didn't count on T+3 dumping in BML.