Display size is the setting that makes an iceberg-order an iceberg. You send 50,000 shares with a display of 500, and the book shows 500. Each time the tip fills, a new slice is exposed.
Most venues randomise or require a minimum display to stop gaming, and each refresh normally goes to the back of the queue-position at that price, which is the real cost of hiding.
Example: 50,000 shares at 25.00 with 500 displayed means up to 100 refreshes. If each refresh loses your place behind an average of 3,000 shares, you may trade only a fraction before the price moves. Larger display sizes fill faster but advertise more of your intention.
Related: iceberg-order, hidden-order, order-slicing