This may at some point grow into a larger discussion - perhaps a Melee Academy post (remember them?) or something of that sort.
But for now, it's just a brief observation I'd like to make.
In my younger days, especially running abstracted combat with systems like AD&D 1st edition, Rolemaster, and GURPS 1st edition using the mapless basic combat rules, combat generally took place in rooms.
PCs moved more-or-less as a group, and if they attacked the occupants of a room they did so by moving into the room. Fights took place inside a location.
These days, however, fighting in rooms is the exception. Running GURPS 4th edition with a group that emphasizes the details of advanced, tactical map sheet combat, our fights rarely take place in rooms.
They usually take place in hallways and doorways. Most of the fights the PCs have been in recently have been in chokepoints. Those chokepoints are doorways, narrowed placed in rooms in a few rare cases, and a lot of hallways. The PCs just refuse to fight where they can't narrow down the enemy to a maximum of 3 across unless that's the only way at all to fight . . . and then only if they want that fight for some special reason.
GURPS generally rewards this . . . but it's interesting. Rooms aren't combat locations until the enemy can stand off and ignore ranged and spell attacks for an unlimited amount of time. Or can inflict so much pain, so quickly, that the PCs have to move into the room. Even in the latter case, the foe is often unable to force the issue unless the PCs really decide they must win the fight quickly. Given the relative caution of my current group, this means fights in hallways and disengagements otherwise. It's an interesting change from how we used to see RPG combat.
It's an interesting change from a general melee to a fight between tight formations of extreme tactical precision.