The current URC format is also one that makes sense once you concede a double round robin isn't viable.
You have 4 equally sized divisions. You play everyone in your division Home & Away, and you play everyone else Home OR Away. Your division consists of your own countries teams*. Top 8 teams qualify for playoffs based on overall league performance, with no "in league" automatic reward for topping division (and automatic qualification for the Champions Cup for the Shield winners is gone this season too IIRC).
Twas a big improvement from the 14 team model (Two Seven team conferences with half the teams from each Union, play everyone internally twice and everyone externally once, except for your local rivals who you would get two extra games against), but even that made "slightly" more sense than the 18 team model. I can't still wrap my head around what those maniacs came up with. Two linked conferences of 4, another two of 5, an "in theory" Japanese based team playing half their games from Singapore against teams 8 time zones away from them. If you were in the 4 team conference you played a sensible-ish schedule of everyone in own division twice, everyone in partner division once and half of the teams in the "other division", but the 5 team conferences didn't even get to play every team in their partner division, nor did they get home and away against everyone in their own group.
What maniacs ever thought that is an appropriate commercial format I'll never know. Seppos have some of the weirdest and most confusing league structures known to man, but at least their scheduling for the NFL has consistent and logical repeated fixtures and a specific directive to aim for (play fixtures against every team at least once every four seasons).
That's not to say Australians won't accept unequal or illogical or supremely commercially driven (rather than competitive integrity) fixture formats: the AFL and NRL prove that, but there needs to be something more than LOL, you figure it out.