The unseemly game-playing over the date of the election seems to be having an effect, with the Herald this morning calling for the date to be fixed by law. As I've said before, I think this is a good idea. The current system invites abuse by the government of the day, with elections being timed in an effort to maximise government support. This is not something we should tolerate in a democracy.
The one problem with this idea is that it makes it difficult to resolve a mid-term breakdown of government. But as the Herald points out, this can be resolved; Germany requires a "constructive vote of no confidence", meaning that in order for a government to fall, a replacement must be available. Alternatively, in the event that no alternative government is available,
Germany allows an early election to be called only with the support of the upper house; in New Zealand, with our single-chamber system, we could simply require a supermajority.
The Herald suggests a referendum on the subject, and I agree. This is not a change Parliament will make for itself - our major parties will not give up their privilege - and therefore we must make it for them.
Correction: I was wrong about Germany and the upper house above; see Wikipedia for the proper details. Governments can vote themselves out of office and thereby force an election, but ther's effectively a waiting period in which other parties have a good chance to form a government. Such a system would be easy to adopt here, provided we ensure that the government puts confidence motions to the House on a regular schedule.