A major franchise league occupies a fixed stretch of the calendar during which little other cricket is played. That window is negotiated within the international schedule and defended commercially.
Overseas availability is the core requirement
A franchise league's appeal rests on squads containing players from several countries. Those players are contracted to their national boards, and national commitments take precedence.
If international fixtures are scheduled across the league's dates, boards recall players and squads are hollowed out mid-tournament, which damages exactly the product that was sold.
The window therefore exists to guarantee availability. It is written into the international calendar as a period where full international fixtures are largely avoided.
Broadcast contracts assume the window
Rights are bought on the expectation that named players will appear. A buyer paying for a tournament featuring the world's leading cricketers has priced that assumption into the fee.
Contracts may not name individuals, but they specify tournament dates and squad composition rules, and a league that could not deliver recognisable squads would face renegotiation.
Protecting the window is therefore a contractual necessity rather than a preference, and leagues invest heavily in the governance processes that allocate it.
Exclusivity also means no competing cricket
Even without player conflicts, a rival tournament in the same weeks divides the audience and the advertising spend available to reach it.
Other franchise leagues have moved their dates to avoid the overlap, which produces a calendar where competitions queue rather than compete.
That queueing has filled most of the year, and new leagues now face the problem of finding any window at all, which is why several have launched into awkward seasonal slots.
The window shapes domestic cricket too
A country hosting a large franchise league schedules its domestic first-class season around it, since venues, officials and broadcast facilities are all committed elsewhere during those weeks.
Ground staff preparing pitches for the tournament cannot simultaneously prepare them for other cricket, and stadium availability is the practical limit.
The knock-on effect is that domestic competitions occupy the least attractive parts of the calendar, which affects their own audiences and their ability to attract sponsors.
Weather sets the outer boundary
The window cannot simply be placed anywhere. Monsoon and extreme heat rule out large parts of the year in some cricketing countries, narrowing the viable months considerably.
Within those months the league must also avoid clashing with major events in other sports that compete for the same advertising budgets and the same evening audience.
What looks like a fixed tradition is therefore the intersection of climate, international scheduling and the media calendar, with very little slack in any direction.
