Why Full Calendars Break Small Businesses

Ryan Haylett

Your calendar's booked solid for the next six weeks. Every crew is dispatched, every hour is sold. Is that a great business, or a business about to fall over?

Dave Rowley

Um, I mean... the first one? That's the dream, right? Full calendar, full revenue.

Ryan Haylett

That's the instinct. And I think it's, it's, it's half right in a way that hurts you. Here's the mystery. Why are the busiest small businesses the ones that run weeks behind? Plumbers, landscapers, agencies. Booked flat out, always late, team fried.

Dave Rowley

I've seen it in dev shops. Every hour of the sprint accounted for, and then one bug blows up the whole thing.

Ryan Haylett

Right. And there's math on it. A British mathematician, Sir John Kingman, published a queuing formula in 1961. According to the write up on All About Lean, it estimates how long work waits, based on two things. How busy the system is, and how much variation there is.

Dave Rowley

Variation meaning...

Ryan Haylett

Jobs don't show up evenly, and they don't take the same time. One's a ten minute fix, the next one you open the wall and find rot.

Dave Rowley

Okay, so where's the surprise?

Ryan Haylett

The busy part of the formula is utilization divided by one minus utilization. At fifty percent busy, that number is one. At eighty percent, it's four. At ninety, nine. At ninety five, nineteen.

Dave Rowley

Wait, wait. So ten more points, eighty to ninety, and the wait more than doubles?

Ryan Haylett

More than doubles. And the source says the closer you get to a hundred percent utilization, the closer you get to an infinite queue length.

Dave Rowley

Infinite. Come on. Nobody's waiting forever.

Ryan Haylett

Fair. It's an approximation, and the article says so itself. In real life people cancel, you work weekends. But the shape is right. A ScanQueue explainer on queuing theory says above about eighty five percent, and wait times rise sharply.

Dave Rowley

So it's not a ramp. It's a cliff.

Ryan Haylett

Flat, flat, flat, then basically vertical.

Dave Rowley

Give me the ugly version. What does the cliff look like on a Tuesday?

Ryan Haylett

A tech gets stuck in traffic. Or a part shows up two hours late. Or a routine appointment turns into, oh, there's damage behind that. With slack, you absorb it. With zero slack, those two hours have nowhere to go, so they push every job after them. Tomorrow's already full, so the delay carries over. Next thing you know, one bad morning is a three week slip.

Dave Rowley

It's a server pinned at full CPU. One little spike and every request behind it just stacks up. Yeah.

Ryan Haylett

Same shape. But the hard part isn't the math. It's the feeling. You look at an empty Tuesday afternoon and your stomach turns.

Dave Rowley

I'd fill it. I, I, I would absolutely fill it.

Ryan Haylett

Everybody does. Employee brain says idle time is waste. CEO brain has to see that empty block as doing a job. Unlearning that reflex might be the hardest shift for a founder.

Dave Rowley

Okay, so what job is it doing?

Ryan Haylett

Shock absorber. Good service businesses design the schedule around eighty to eighty five percent, on purpose. The leftover room handles emergencies, lets you grab a same day job at a premium, and cuts the overtime you'd otherwise pay for catching up.

Dave Rowley

But I'm still paying people for that empty fifteen percent. Somebody's gotta fund it.

Ryan Haylett

Pricing funds it. Two moves. Raise prices ten to fifteen percent, and let go of the bottom ten percent of clients. The high maintenance, low margin ones.

Dave Rowley

Hold on. Raise prices and lose clients? That sounds like shrinking.

Ryan Haylett

Rough math, and I'm assuming those clients are average size. Keep ninety percent of clients, charge them ten percent more, and you're at about ninety nine percent of the old revenue. Charge fifteen more, about a hundred and three and a half. Revenue's roughly flat.

Dave Rowley

And you've got ten percent of your capacity back.

Ryan Haylett

Right. Same money, less load. And the clients you shed are usually the ones who eat the most hours, so it's probably better than that.

Dave Rowley

Okay. What do people do this week?

Ryan Haylett

Two things. One, audit capacity against what you've actually promised. Person by person, crew by crew. You'll probably find a hidden ninety percent plus spot, someone everyone leans on.

Dave Rowley

Always that one person, yeah.

Ryan Haylett

Two, put a recurring half day buffer on the calendar. Protected. Not for new work. For friction.

Dave Rowley

And if nothing goes wrong that week?

Ryan Haylett

Then you catch up, or you sell it as a same day slot. Either way it's paid for itself.

Dave Rowley

So the empty block isn't, um, wasted overhead. It's what lets you charge more and show up on time.

Ryan Haylett

That's it. Buffer is pricing leverage and customer trust. If you want help engineering systems that hold up, modularity.us.

Dave Rowley

So the full calendar's the one that falls over. Good to know.