That is... excessive. I tend to make a similar hallway, but the entrance to the fort is right at the beginning. In the case of attack, I close off that convenient entrance into the fort so that enemies must walk the long corridor of death. This also ends in a danger room, but has several more bridges to serve as airlocks to help break up the stragglers. I like to build a longer drop to the sides and make it a meandering 1-tile pathway over the drop. I thend periodically place weapon traps to help encourage "dodging" into the abyss. The abyss eventually houses a handful of captured FBs for !Fun! or is where I actually put the marksdorfs and their fortifications. Putting the entrance to the fort 100+ tiles away from the entrance to the caverns/surface just makes it take -forever- to access the caverns and surface for logging, hunting, plant gathering, fishing, or just building megaprojects up there.
If there is no proper hill/mountainside to build into, I can't very well leave the entrance to my grand fort as nothing more than an undignified hole in the ground, can I!? I then build a bit of a surface structure mostly to add some dignity to my entrance. Usually this involves a walled in barracks (lined with fortifications) generally only accessed from below. I say barracks, but this also includes dining room, archery ranges, sleeping quarters... a general purpose To one side is the quick ramps down for general comings and goings (including caravans) that has statues and paved roads- a courtyard all prettiful-like. The outerwall has a bridge that closes off entrance to this, and instead routes enemies around to the other side of the barracks. Here, they have to walk a long trapped corridor while under fire from the marksdorfs in the barracks before finally entering said barracks to do battle with the my soldiers. If there is an aquifer/river I'll work in a drowning chamber. I tend to put noble rooms stacked on top of these in a tower, with the king's room being on top and made of glass.
If there is a hill/mountainside, there still needs to be a grand entrance hall. I'm talking multiple stories with carved out/engraved columns. All of this is carved from stone, ofc- dirt is for kobolds! Like above, this also features a bridge that routes enemies into a different direction- I can't have them toppling my statues! In this case, I typically utilize pit traps dug 10+ z levels down ending in FB/Titan lairs.