The client mentions, quite mildly, that she thought the utility door had been moved.
You say it hasn't, because as far as you know it hasn't. Your colleague, sitting next to you, says actually yes, that changed. Short pause. The client looks between the two of you, not annoyed, just recalibrating slightly, and you say you'll confirm and move on to the next item.
Neither of you was wrong. You were going off the drawing set, which is current. He was going off a message the client sent about three weeks ago, which he happened to see and you didn't. Nothing was lost, nothing was hidden, and nobody was careless. The two of you had simply built your understanding of the project out of different pieces of it.
What makes that worth thinking about is that you'd both prepared. You'd done the half hour.
Everybody knows the half hour. Client's at four, so at half three you sit down to get across it. The drawings are open in one window. The WhatsApp thread is open on the phone and you're scrolling back for the thing she said about the kitchen, which you know she said, and which was definitely an afternoon sometime in the last fortnight. There's an email from the engineer that you're fairly sure supersedes something in the drawing set, and the only way to find out is to open both. You ask whoever walks past where the revised layout ended up. At ten to four you're across it.
Which is a peculiar thing to be able to say about your own project. You didn't learn anything in those twenty minutes. Every one of those facts was already yours. You just gathered them into one place, briefly, so they could all be true at the same time.
And then the meeting happens, and it comes apart again. Not because you forget, exactly. It's more that the assembled version was never a thing that existed anywhere. It lived in your head for about forty minutes and then went back to being four separate sources.
So next week you build it again. And because you're building it from scratch, from whichever sources you happen to reach for that day, you build it slightly differently. Your colleague builds his differently again. Both of you are diligent. Both versions are made of real information. They just aren't the same version, and there's nothing anywhere for either of you to check against.
This is usually filed under communication, and that's why it never gets better. The advice is to talk to each other more, and you already do. He didn't withhold the message about the door. He saw it, thought nothing of it, and had no reason to think you hadn't seen it too. There was no moment where either of you could have caught it, because catching it would have meant comparing two versions that only exist in two heads.
The half hour isn't preparation, then. Preparation is deciding what to say and what you want out of the meeting. This is reconstruction, done before every meeting, every client call and every time somebody asks how a job is going, and it gets counted as part of the work because there's nowhere else to put it.
What's missing isn't information. It's one current version of the project that nobody has to assemble. Projectsmate holds the stage, the live drawing, what the client last agreed and what's still open, on the project itself, so the half hour turns into reading rather than rebuilding, and two people reading the same thing tend to arrive at the same answer.
Every project has a current state. At the moment it exists for about forty minutes at a time, in one person's head, and in a slightly different form in somebody else's.