Its never been my experience that you get bumped in line...I have had sell orders in for months and would cancel or let the order expire. I would put in another one and it would fill within a few hours on light volume. I also would have orders in for long amounts of time and put in additional orders for the same stock which would fill within a few day and the older one go untouched. I don't think there is any order to when you place your orders...
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