If you have many teams in an event they can’t possibly play each other so they play a selection of random opponents. This process is known as a snake. To use this system each team needs to have a number they keep all day. Once these numbers have been assigned these fixtures are used. If you don’t want 6 rounds only use the ones you want. We cannot take credit for these tables. They come from Northern Petanque which also has many other good ideas about running competitions.
Snake planner for 8 teams to 30 teams is a pdf to print out and save somewhere. Best way to use these is to have a large blackboard/whiteboard where you write up the fixtures and every round you write up the new fixtures.
If you want to run higher level sophisticated competitions you should think about using the The Swiss System which means the further you go in a competition the better your opponents are. Lots more work in this however.
Modified rolling knockout for 8 teams is also from Northern Petanque is worth looking at for a winner plays winner system.