It is the most vexed issue in rugby, yet establishing a global season is also rugby's highest priority.
For almost the entire professional period there have been attempts to align the Northern and Southern Hemisphere seasons. Everyone agrees there has to be better, more logical flow to the calendar and a longer off-season - ideally 16 weeks between the last game of one season and the first of the next.
Without that extended off-season, players are being stretched too far by the endless physical and mental demands of playing for more than 10 months a year.
It's not sustainable and change is essential but reaching agreement requires compromise or possibly even sacrifice and that's why, almost 15 years since the idea of creating a global season was introduced, the prospect is no nearer.
Talks progress then falter. Ideas are embraced then ditched and every time there is the faintest hint of something actually happening, it's suddenly put in the too-hard box.
It's possible that's, once again, where things are. There has been, in the last 12 months, a renewed appetite among all the major unions to find a permanent solution.
There is a now-or-never feeling and it coincides with the arrival of new executive leadership at World Rugby. Bill Beaumont was elected chairman last month, with Agustin Pichot as his deputy, with a mandate to modernise the governance and put to bed all the game's lingering issues, such as season structure.
He is equally determined to find a solution that works, but just how hard that is going to be became apparent when Rugby Football Union chief executive Ian Ritchie revealed this week how many non-negotiables there were for England.
"The Six Nations, as far as the date in the calendar is concerned, works well," Ritchie told the BBC. "As far as we're concerned, we have a great TV deal and we have stadia that are filled for every game. Why would you want to change something that works really well? So I can't see there being any significant move in that ...
"The autumn internationals work terribly well for us as well. It's early days yet, but it's going to be an interesting few months on the global calendar discussions."
His comments were viewed as evidence there is no hope for change.
But that's not quite how it is. There is probably no hope for radical change, for a total overhaul and a genuine alignment of the calendar. But there is a flicker of hope that there is a less ambitious solution.
The piece of the jigsaw that currently doesn't work for the south and could be better for the north is the June test window.
In the south, it forces Super Rugby to go on hold. It's not a problem for the north, as such. Changing the June window to a July window may not require dramatic change and could deliver big improvements.
It could be that simple. The south could play a 20-week, uninterrupted Super Rugby competition from late February to late June and then the usual test programme in July, with the Rugby Championship and November tests staying as is.
For the north, their season could kick off in late September, move into November tests, Six Nations in February to early April and club finals in June before they head south for July tests.
It's not the radical global season many had hoped for, but this proposal had widespread approval a few years ago before the French and Celts killed it off.
It's not back on the table but, at the moment, nothing is and those who have experience with the way World Rugby does business don't believe there will be meaningful progress until someone has significant leverage to force the issue.
And that will come. No one can say for sure when, but everyone knows it will come as no test matches have been scheduled for June or November beyond 2019. And they won't be, either. New Zealand won't agree to play anyone outside of the Rugby Championship from 2020 until there is a resolution on season structure.
So it might be that there is no progress about a season structure this year or next but, by 2018, a few nations will be getting nervous.
Not every northern union has pockets as deep as England. There will be nervousness at the prospect of not knowing when, or indeed if, they will play the All Blacks after 2019.
When the All Blacks head north, they sell out stadiums and bring big pay days for the host unions.
However things seem, a solution may not be so far away for this vexed problem.