Professional teams spend most of their practice hours in arranged matches against other professional teams rather than in the game's ranked queue. The reason is that ranked play cannot supply what they need.
Matchmaking cannot deliver an opponent of the right standard
There are few teams at the top level, and ranked systems match individuals rather than rosters. A full professional team queueing together faces whoever is available.
The resulting games are usually unbalanced in one direction or the other, and unbalanced games teach very little about execution under pressure.
Arranged practice fixes the opponent in advance, which is the only way to guarantee a match at a comparable standard.
Strategies must be hidden until they are used
Anything played in a public queue can be observed, recorded and shared. A strategy prepared for a tournament would be public before it was used.
Practice matches are conducted privately and usually under an understanding that neither side discusses what was seen. The convention is informal but widely held.
This lets teams rehearse specific plans repeatedly, which is impossible in an environment where every attempt is evidence for opponents.
Repetition requires controlled conditions
Teams need to run the same opening or the same objective sequence many times to find where it breaks. Ranked play does not offer that control.
Scheduled sessions can be structured: a block of games with one map, one composition, or one scenario repeated until timings are consistent.
Coaches also stop and review between games, which a public queue penalises. The practice format is built around analysis rather than continuous play.
The arrangement has known weaknesses
Practice results carry no stakes, so teams take risks they would not take in a tournament. Behaviour under pressure is exactly what practice cannot rehearse.
There is also a trust problem. A team can practise a strategy it has no intention of using, or share what it observed with a third party.
These are managed socially rather than by rule, which is why regions with fewer teams and tighter relationships often report more reliable practice.
Availability shapes competitive geography
A team needs willing opponents in a compatible time zone with low enough latency for the games to be meaningful. That is a narrow set.
Regions with many organisations offer far better practice than regions with few, independently of individual player quality.
This is a substantial part of why teams relocate to established regions. They are moving for the practice environment rather than the tournaments.