“This is the stupidest thing ever,” my daughter whispers to me through gritted teeth, squeezing my hand a little too tight as we shuffle along with our group.

We’re on a Harry Potter walking tour through the streets of London -- a tour for “Muggles” that I thought the 10-year-old would adore since she’s already halfway through her seventh back-to-back Harry Potter book of this trip so far.

When I found the tour online, she had sounded excited to go, and though I balked a little at the $55 price tag, I patted myself on the back for finding what sounded like the perfect mother-daughter afternoon. She would see all the film locations, and I’d get to visit hidden parts of London I hadn’t yet explored. Wins all around.

But as we pushed through the cramped Underground that morning, hurrying to the tour meeting point, my daughter stopped dead in her tracks as she spotted the rest of our group.

“What is this?” she asked.

“Um, it’s the walking tour we’re doing?” I replied.

“Walking tour? You said this was a museum,” she said in disbelief.

I swear I didn’t say anything about a museum, but somehow, while telling her we would be seeing the real-life London film locations of the movie series, she had gotten it into her head that we were going to an exhibit, not a walking tour.

And now, as she watched the tour leader calling out to the group to huddle in as London morning commuters rushed past, I realized she was going to hate this.

My quiet, reserved daughter can’t stand the idea of anyone deliberately drawing attention to themselves by speaking up in a crowd. Yet here was the tour leader, beginning to move us through the busy Borough Market, pointing to a doorway and loudly explaining that this site was the stand-in for the entrance to the Leaky Cauldron.

“Could he not talk so loud,” my daughter angrily whispered. “This is stupid. I want to go home.”

Uh, we’re not going home, I told her, not after I shelled out this money.

We pressed on, me hoping she’d come around as the tour wore on. But even two hours in, her mood never lightened and we left the group the first chance we got as it began wrapping up. The day was a disaster, the tour a failure, my perfect mother-daughter outing a washout.

Disappointments are nothing new to parents and they’re nothing new to seasoned travellers either. Visit enough places and you’re going to eventually encounter a few duds. But somehow, when you’re on a huge journey, a six-month tour of Europe that you funded by selling off your house, these disappointments hurt a little more.

This is supposed to be the trip of a lifetime, you tell yourself. Every day has to be fabulous. There isn’t going to be another chance to do a trip like this, so everything has to go right.

But of course, not everything can go right. It’s just the laws of statistics: the longer the journey extends, the bigger the risk for small disasters.

Mercifully, we’ve had no major disasters on this trip, so far. But we have made our share of mistakes. We stayed in one town a little too long, for example, and when we ran out of things to see (or at least sights we could afford to see), we began driving each other crazy by holing up in a too-small apartment, getting into arguments and on each other’s nerves. Though my husband was happy to stay in that town longer, the rest of were ready to move on, but couldn’t.

And there remains the fundamental problem of long-term family travel: it’s impossible to plan for what everyone will need from the journey. With short vacations, it’s simpler. When you book a week at a family resort or cottage, everyone knows what they’re in for: lots of relaxing, some beach time, some sunsets. A trip to a big city, you’re there to see the sights. You end the vacation happy because everyone got what they expected

But with longer family travel that goes on for months, it’s not so simple. Eventually, your travelling styles clash.

I’ve learned I tend to get itchy feet after about a week in a new place. While my husband is happy to just hang out in cafes and read the local newspaper, I start worrying we aren’t doing enough, not seeing enough of the rest of the country, not getting maximum bang for our travelling buck. I also tend to be more interested in seeing the natural wonders of a new place, the countryside, while my husband prefers cities.

Or, at least, he thought he preferred cities.

We recently found ourselves in a small cottage outside of Killarney. My husband hadn’t been much interested in seeing that part of Ireland; he really preferred the rich history of Dublin. But I booked us a cozy cottage out of town that happened to have a woodstove. In Ireland, most fireplaces burn peat for fuel, not wood, and I quickly learned peat is more difficult to light than you might think. Okay, to be quite honest, my first attempt at getting that fire going ended in a smoke-filled mess.

“Move over, move over. This is a man’s job,” my husband said to me with a grin, as he pushed me aside and got to work building up a new fire.

He spent the rest of the evening happily tending to that fire -- and every fire each day after that as well. He gathered up peat strips from the woodpile and chopped up hardwood logs using an axe to make more kindling, and soon the kids were learning to do the same using hatchets.

“I love this place,” he announced to me the second day. “Can we stay here another week?”

“Yeah, yeah!” the kids chimed in. “Can we? Can we?” They too had quickly fallen in love with the place, the kindling, and the dogs who lived on the property.

“But I thought you didn’t like the countryside,” I teased my husband. “Didn’t you tell me you wanted to stick to cities?”

“Well, I was wrong,” he admitted.

That stay in the “country” turned out to be exactly what we needed just then, and made it clear to us that it had been a mistake to just focus on cities.

Yet it’s a mistake we never would have foreseen when we planned the trip. We’re realizing though that you kind of learn as you go on long-term travel. You can’t predict how your needs are going to change as you go.

Which is why I’m now glad we didn’t book every single thing before we left. We mapped out the basics and we booked the flights, but we also took the advice of others who had done similar long journeys and built in some flexibility. That way, when mistakes happen, we can brush it off, make a shift and press on to the next great moment to come.