As people may know (though there's no particular reason why a non-Brit should take any particular interest), in the UK we're busy choosing a new leader for the Labour Party after Labour's dreadful showing in the recent general election.
The considerations are very different in the US vs the UK, because our political system is so different -- the party leader, whatever the party, has to lead the party in the House of Commons, as does Nancy Pelosi have to lead the Democrats in the House of Representatives, so she or he has to be able to command the support, whether enthusiastic or not, of all wings of the party (or, in Boris Johnson's case, to purge elements who can't be reconciled to the leader's policies) -- so the considerations that guide us over here are very different from those in the US.
However, what this does mean is that whoever becomes leader of the Labour Party in early March will spend the next four or five years both attempting to hold the government to account in Parliament and also -- at least as importantly -- spend that time developing policies that the whole party can unite around and which are attractive to the voters.
I'm not at all sure that would be possible in the US, but it struck that in many ways our system of the opposition party choosing well in advance the person who will lead them into the next election makes a lot more sense than selecting one only a matter of months before the actual election.