The only time a Finnish government coalition has failed due to a loss of confidence was in the early 80s. Prime ministers occasionally change mid-term and minor parties sometimes leave the coalition, but the coalition always continues until the next regular elections.

And the reason for this stability is trivial. If a party leaves a coalition and the coalition loses parliamentary majority, that party is effectively a major party. Potential prime ministers are rarely stupid enough or desperate enough to give small parties that kind of power. Instead, they prefer making the coalition a bit wider by adding another small party or two.

We also have the Swedish People's Party, which specializes as a reliable coalition partner. They are willing to collaborate with pretty much anyone. As long the coalition agrees to uphold the rights of the Swedish-speaking minority, they will give it another 4-5% support without too much drama.

Australia is a good counter example.

We use preferential voting and haven't had a minority government, that is a government formed by coalition as the result of an election since 2010. We still typically have 2 major parties and 3-4 minor parties that can (but by no means always) hold the balance of power, particularly in the senate. It means that the govt has to compromise more often to get bills passed, but the minority parties rarely hold legislation hostage (barring things like the Housing Future Fund, which was a dog's breakfast).