You make a ruling in session three. A player falls 10 feet during a fight, and you quickly decide it deals 1d6 damage. Everyone nods, the rogue takes four damage, the game continues. No problem.
Session seven. Different player, different context, but someone falls 10 feet. You say 2d6 damage because you forgot your earlier ruling, or because this fall feels more dramatic, or because you've been thinking the first ruling was too generous.
Congratulations. You just told your players the world doesn't follow consistently. It follows your mood. Immersion, cracked.
Why Consistency More Than Correctness
Your players aren't memorizing the eight rulebooks. They're learning your world through pattern recognition. When you rule that shield bashes can shove enemies backward, they start planning tactics around it. The fighter positions themselves between the archer and the cliff. The wizard readies an action to cast Grease right before the shield bash. They're thinking three moves ahead because they trust the mechanic.
Then you change your mind. Maybe you decide shield bashes are too strong, or you forgot you allowed it before, or you read something in the books that made you second-guess yourself. So the fighter tries their signature move and you say "actually, shields can't do that." The player feels cheated, and rightfully so. You taught them the rules, then changed them midgame.
The ruling doesn't have to be perfect. It has to be yours, and it has to be reliable. Think of it like gravity. Your world's gravity might be slightly different from Earth's - maybe people can jump a bit higher, or falling is slightly more forgiving. That's fine! As long as it's always that way. Once players internalize that "in this world, we can jump six feet high," they'll plan around it. They'll leap across gaps, jump onto tables during tavern brawls, and suggest acrobatic solutions. Your consistent ruling just enriched their tactical options.
But if gravity changes between sessions, players stop trusting the ground beneath their feet. Literally.
How to Stay Consistent
The first and most critical step is to write it down immediately. Keep a "House Rulings" section in your DN notes, either a dedicated page in your notebook or a running document on your device. The moment you make a call on something not in the books, jot it down. Don't wait until after the session when details get fuzzy. Right there at the table: "Shield bash contested Strength roll, winner chooses to push or be pushed, loser moves five feet." Date it if you're thorough. Include context if it matters. This isn't busywork - this is building your world's physics engine.
Review between sessions. Before each game, skim your rulings log. Refresh your memory. If you realize a ruling was unbalanced or exploitable, don't spring a change mid-session. Announce it at session start: "Hey, remember shield bashes? I've been thinking they're a bit strong. Going forward, contested check but the defender gets +2 if they're braced. Sound fair?" Players respect iteration when you're transparent and give them time to adjust. Let players track it too. Encourage note-taking. When someone says "But last time you said we could do this," they're not challenging your authority - they're helping maintain the world's integrity. Thank them. Check your notes. If they're right, own it: "You're absolutely right, good memory. We're doing it that way." If they're misremembering, show them your notes: "I've got it written here as working differently, but let's double-check after the session if there's confusion."
When you must change a ruling, explain why. Players understand that you're learning and balancing on the fly. What they can't stand is arbitrary reversals. "I ruled last time that you could jump 15 feet because I forgot to account for armor weight. Going forward, heavy armor reduces jump distance by half. Fair warning for everyone." That's honest. That's respectful. That keeps immersion intact because you're explaining the physics correction, not just changing your mind.
Tier your rulings in your notes. Mark some as "temporary call, revisit later" versus "permanent house rule." When you make a quick call under pressure, add a question mark or "temp" tag. Between sessions, think it through properly. Then either commit to it or revise it before it comes up again. This keeps you from accidentally cementing bad rulings while also letting you make fast decisions during play.