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While this sounds kind of silly, I'm a DM and trying to settle on a question a player asked me. In the game I use a battlemat and place all creatures in melee adjacent to each other. However a player asked me if being within 5ft meant that they could reach something that was one square away from them.
I can see their reasoning that if you imagine two sword fighters having at it, they aren't shield to shield and slapping each other but moving in and out of range with a significant gap between them.
Aside from practical, if a neutral creature who's foe to neither wanted to run in between two sword fighters my imagination says they could, but per how I place minis on a battlemat there's not a gap to move through.
Would it be a bad/game-breaking reason to leave a gap and call 5ft that gap, or is it implied more directly that creatures are small enough within their squares that the combined difference means adjacent creatures are actually 5ft away?