Elections tend to be less frequent under Proportional systems, than under First Past the Post, which incentivizes early dissolution if a minority government are elected. No such incentive exists in a proportional system, so minority governments lat their full term.
Majority governments are also possible, if a party has truly earned a majority from the voters.
Read more below...
On election frequency:
On minority/majority government functioning:
In proportional representation, single-party majority governments (with more than 50% of the seats) can still form - as long as an actual majority of the voters (more than 50%) truly supports that party - or if they win 14 or more of the 18 district seats.
A more common outcome in proportional systems, however, is majority coalition governments - made up of a combination of different parties, none of whom have earned a majority in their own right. In these systems, parties are *forced* to get along and negotiate with each other, to make progress. Decision-making can be slower, but that's a good thing - the quality of decision-making tends to be better when it isn't pushed through by a single party.
Jacinda Ardern, Prime Minister of New Zealand (which uses MMP) said in a recent interview, with regards to needing to negotiate with coalition partners to pass any legislation... that 'she enjoys this part of the job.' “I don’t get exasperated or frustrated by it. ... Oh, you know, sometimes you want things to be resolved a bit quicker, but I go in knowing I have to have those conversations. I’m only in government because two parties decided to work with us.”'
On the Brexit mess in the UK, from the same article: “The only thing I’d say is that, as much as we inherited the Westminster system, we thankfully also have moved to an MMP [mixed-member proportional] system,” she said. The system makes the sort of deadlocks witnessed in the Commons this year much less likely. “We have consensus really built into our system. It changes, probably more than we know, the way we work… By our very nature, I think we probably do things a bit differently.”
New Zealand offers one anecdote of how coalitions work by consensus. There are many other examples.
With at least 2 parties needing to agree on every bill, there’s less chance of any single party is pushing its own agenda or acting unfairly, because there is a built-in check-and-balance. Under First Past the Post, a party can put policies in place without the support of a majority of the population. Then, when the government changes to the other colour in a few elections time, their first year in government is often spent undoing the worst policies that the previous government put in place.
Countries with Proportional Representation actually tend to have more stable long-term policies than those with First Past the Post, and legislation is better-considered before being passed.
No one likes unstable governments, and under the First-Past-The-Post system, minority governments are indeed unstable, because minority governments will readily dissolve and call a fresh election, knowing that they have a good chance of winning a 'false majority'.
One of the great things that we see in countries with proportional representation is that there is actually more stability, and less frequent elections, because minority governments won't voluntarily dissolve - they know that there's very little chance of them winning an unfair majority!
Here is a great opinion piece from island publisher Paul MacNeill, addressing the 'suspect definition of stability' that seems to be held by many defenders of the current, First-Past-the-Post system.
Under our current First Past The Post system, parties often feel little incentive to work together, because being oppositional, driving polarization, and then triggering an election may lead to a result that the party likes better (a false majority in their favour).
Under MMP, by contrast, parties are forced to work together - 'opposition for the sake of opposing' disappears, and coalition or minority governments tend to serve their full term, rather than calling early elections.
With MMP the make-up of the legislature won’t change dramatically from one election to another - rather, there will be ‘course corrections’ - accountability for low performers and the welcoming of new voices, without dramatic swings from left to right. With little to gain from triggering an election, parties have more reason to co-operate.