Repeats come sooner when:
Groups are small. A group of 8 has far fewer possible pairings than a group of 20.
The format is Mixed Gender Rotating Partners, which roughly halves the possible partnerships.
The same core players attend every week.
To reduce repeats:
Use larger groups where your courts allow.
Tap Admin > Matchup Stats to see how many pairings repeat, and apply a suggested swap. A swap changes that round without regenerating.
Regenerate the date if one week looks unusually repetitive.