Most professional sports are built around a season with a beginning and an end. A league sets a fixture list, plays it, crowns a champion, and then goes quiet for a stretch while contracts get negotiated and bodies recover. Tennis does not work that way. The professional tours run an almost continuous global calendar, and the gap between the last event that matters in one year and the first that matters in the next is measured in weeks rather than months.
The reason is not that anyone designed the sport to be relentless. It is that the tennis calendar is the product of several independent parties, each with a legitimate claim on a player's time, and none of whom has the authority to shrink the whole thing. The season never really ends because no single organisation is in a position to end it.
