I've been asking myself this question recently. Would trades be more likely to work out as position size increases? Most intraday traders notice quick buying or selling spikes to signify support and resistance. So theoretically, if I got into a position with enough shares to create a noticeable push in a certain direction, that could influence other traders as a sign to trade in that direction as well, where they might have been on the fence about direction. Could such a factor possibly influence win rate by a few percentage points... I'm not talking about huge slippage, but something noticeable.