Why enter Egg Heist through the blue door?

In Chaos Mode, you identify the layout by matching the mini-map around the main door to the possible layouts. Each map is one of a set of known layouts, so once you have a match you stop exploring blind and start moving with a plan.

That matters because eggs do not appear just anywhere. Nests sit at fixed spawn positions, and only in certain room types such as large rooms and the locked key rooms. Each map has two locked rooms whose doors need a blue key. In a Chaos run almost no eggs lie in the open, so those two locked rooms are where the run is won or lost. If you know the layout, you know where they are before another team gets there.

The layout also tells you how far you are from the beach. Whoever carries the giant egg transforms into it, loses all combat abilities and can only jump and roll or dash. Your team has to escort that player to the boat, so you want the route back worked out before anyone picks the egg up. Loot chests are spread through the dungeon as well, and knowing the layout helps you decide which ones are worth the detour.