Two trips of the same length can differ enormously in cost depending only on how many places they include. The reason is that movement, not time, drives most of the spending.
Transport is the lumpy cost
Every additional city on an itinerary adds a transfer, and transfers are priced as discrete events rather than as a share of the trip.
A week in one place involves an arrival and a departure. The same week across four places involves five journeys, each with its own fare, its own transfer to the station and its own margin for error.
Those fares are also the least predictable element of a budget, because they respond to booking date, day of week and demand in ways that accommodation rates do so less sharply.
Accommodation rewards longer stays directly
Properties and short-let hosts price weekly and monthly stays below the nightly equivalent, because a single long booking costs far less to service than seven separate ones.
Changeover work, cleaning and the risk of an unsold night all fall with length of stay, and the discount reflects that rather than generosity.
The saving is largest in apartment rentals, where the fixed cleaning charge is spread across more nights and becomes almost irrelevant on a long booking.
Local knowledge compounds
A traveller arriving somewhere new pays a premium for not knowing where things are. The first meal is eaten near the station, and the first purchases are made at the first shop found.
After several days that premium disappears. The traveller knows which market is cheaper, which bus reaches the beach and where a set lunch is genuinely good value.
Constant movement resets that learning to zero repeatedly, which is a real cost even though it never appears as a line in any budget.
Self-catering becomes viable
Buying food to cook only makes sense with a kitchen and enough nights to use up what is bought. One-night stops make both impossible.
A longer stay allows a mix of eating out and cooking, which changes the daily food cost substantially without requiring any sacrifice in what is eaten.
It also allows a traveller to shop at markets, which are usually cheaper and more interesting than the options clustered around a station or a monument.
The trade-off is genuine
Slow travel means seeing fewer places, and for a first visit to a region that may be the wrong choice entirely.
What it buys is depth and a lower daily cost, which is why it suits longer trips and repeat visits more than it suits a single short holiday.
The practical compromise most travellers reach is a base with day trips, which keeps the accommodation discount while still covering ground.