AFL football is such a moveable feast these days, the landscape and the metaphorical goalposts shifting so rapidly, that well-worn conventions count for a lot less than they once did.
History is less of a guide and precedents are less important. In a way, it means that familiar customs that still have some relevance in the modern AFL can be clung to even more tightly. Or maybe it's just me.
But as someone whose business has been not just analysing what has happened on the football field but what might happen, there's one marker to which I've been particularly wedded for just on two decades, and which I think even now still stands up pretty well.
We call it the "Round 7 Rule". It's a sort of milestone about teams' chances of making the final eight. And basically, it says that if a team isn't in the top eight at this point of the season, it's more than likely it won't be when the finals start.
We've now had 20 completed AFL seasons since 2001. In 18 of them, the top eight has changed by a maximum of just two teams from the end of round seven to the end of the final home and away round.
There was a period between 2002 and 2010 - nine seasons - when only once did more than one team that hadn't been nestled inside the top eight come the end of round seven end up playing finals.
Eight times there's been just one team make it from outside to a finals campaign, seven times it's been only two teams, and on a couple of occasions, none at all.
Eight times there's been just one team make it from outside to a finals campaign, seven times it's been only two teams, and on a couple of occasions, none at all. Across 20 seasons, the average number of changes has been less than one-and-a-half.
That average includes 2019, when there was, by comparison, an absolute flood of change with four teams inside the top eight after seven rounds dropping out.
Mind you, those four teams - Fremantle, Adelaide, Port Adelaide and St Kilda - were even then only fifth, sixth, seventh and eighth, to be replaced by the four teams immediately beneath them - West Coast, Greater Western Sydney, Western Bulldogs and Essendon.
So, whilst we talk a lot about the evenness of the competition, and how any team can beat any other on a given day, there's also a degree of consistency about results throughout the course of a season. Sure, there's the odd exception. Richmond in 2014 had won just three games by the end of round 14 and was a dismal 16th on the ladder before reeling off a string of nine wins in a row to reach an elimination final. In 2017, Sydney was winless and stone motherless last after six games. The Swans then won 14 of their last 16 games to finish sixth.
But as a pretty steadfast rule for a long time now, what you've seen from a side to this point of an AFL season is what you're more than likely going to see from it for the remainder. And taking a look at which teams are currently outside the top eight, you could argue that in 2021 it's even more likely.
The "also-rans" right now, in order, are Fremantle, Gold Coast, GWS, Carlton, Adelaide, St Kilda, Essendon, Hawthorn, Collingwood and North Melbourne.
Do any of them strike you as teams which are in completely unexpected territory? Sides which have clearly under-performed thus far? Or rocked by a huge list of injuries to key players who may return on the run home to help a late run at September? I'd argue just one - St Kilda.
Collingwood's woes have attracted plenty of attention this season. But the Magpies weren't exactly flying last year, either, limping into eighth spot having barely won half their games before producing one of the biggest finals shocks of recent times, upsetting West Coast in Perth in an elimination final.
That, certainly, was a monumental effort, but Collingwood's thrashing at the hands of Geelong the following week in a semi-final probably offered a truer reflection of the gap between the Pies and the top end of the ladder.
GWS, like Collingwood, has played in a recent grand final, but the Giants were a mere shadow of that 2019 team even by the end of last season, and missing finals again would hardly prove much of a shock.
As for St Kilda, well, who knows with the Saints at the moment, thrashed three weeks out of four before themselves last Saturday thrashing Hawthorn.
What we do know is that the Saints have a particularly tough draw. Nine of their last 15 games are against the current top eight, two each against Geelong and Sydney, and they still have five interstate trips to make, including Cairns, Brisbane and Perth.
And who would they replace in the eight, even allowing for a big recovery? Surprise packet Sydney would be the suggestion of most people, but the Swans are 5-2 and have already knocked over three of last year's top four in Richmond, Geelong and Brisbane. That doesn't feel like a "snow job".
It's going to be super tough for St Kilda to make it from here, even if the ladder has the Saints only one win outside the top eight. But don't just take my word for it, take history's. Because while there isn't much certainty in football today, the "Round 7 Rule" is a rule of thumb still more reliable than most.