A large franchise tournament occupies a fixed block of the year, and the rest of the cricket calendar has organised itself around that block. The effects reach every country that plays the sport.
A protected window is a scheduling decision
When a competition is significant enough that the best players want to be in it, boards face a choice between scheduling against it and scheduling around it.
Scheduling against it means fielding weakened squads or forcing players into a choice, both of which reduce the value of the international fixture.
Most boards therefore avoid the period, which converts an informal preference into an effective global window without any formal rule creating one.
Bilateral series moved rather than disappeared
Series that once occupied the vacated months were pushed into other parts of the year, and those parts were already occupied.
The compression shows up as shorter tours, fewer matches per series, and more limited-overs cricket relative to the longer format.
It also produces fixtures in marginal weather, because the good weather in a given country is a fixed and increasingly contested resource.
Player workload became a negotiation
Central contracts once guaranteed that a board controlled a player's year, and the franchise era introduced an alternative employer for part of it.
Boards responded with no-objection certificates, contract clauses and in some cases limits on how many overseas leagues a contracted player may enter.
The arrangements differ by country and change frequently, but the underlying tension is constant: two employers want the same weeks from the same body.
Other leagues positioned themselves in the gaps
Once one window was established, competitions in other countries were built into the months that remained available.
The result is a near-continuous franchise calendar, with players able to move between tournaments for most of the year if they choose.
That option is why some players relinquish central contracts, since the accumulated franchise income can exceed what a board offers.
What it changed for the longest format
Test cricket requires long unbroken periods and produces less revenue per day than a short tournament, so it is the format most exposed to compression.
Boards with strong domestic income can protect it; those without have fewer matches to sell and less room to schedule them.
The divergence between countries in how much long-form cricket they play is therefore a scheduling outcome rather than a statement about what any board prefers.