For the most part I think they do a great job. I also think they look at kids ages first and go from there.
Or first time cruisers paired with folks with many cruises under their belts.
Cruise 1: We were seated with a family of 4 who had a daughter my kids age and a young son who were platinum (had no clue what that meant at the time, but was impressed with their cruising skills) We had second seating and I like to think they moved to first seating because of the young one because we did not see them the rest of the cruise at dinner.
Cruise 2: We had second seating and asked to switch to main before we even hit the dining room, so no idea who we might have had. But we had no tablemates.
Cruise 3: Just us
Cruise 4: Just us
Cruise 5: Just us
Cruise 6: Not a good match. The kids ages matched our kids but the conversation was awkward...like no one was talking to each other and there was a lot of menu studying going on. They were also on their 6th cruise and were gold just like us..which we chatted about for 2 minutes before dead silence. We requested to be moved and were to our own table.
Cruise 7: Just us
Cruise 8: Just us
Cruise 9: WONDERFUL family from Canada on their first cruise. We still keep in touch on FB Kids were the same age range as ours and they were super sweet and friendly.
Cruise 10: Just us
Cruise 11: Just us
Cruise 12: Started off nice, one daughter same age as my daughter, and home schooled like ours and I think it was their first cruise. They were travelling with her father who was not feeling well (sea sick) and I felt so bad for him. As we were talking to each other the dining team came up to take our requests and the mom told them (and the whole table) that she was allergic to melon and that she could not be at the same table if it was being served there. Sadly, my daughter loves melon and cantelope and would sometimes have it for dessert or instead of a salad. We requested a dining change the next morning and explained why. They were nice people, but I didn't want to be responsible if my daughter ordered something that flared up this poor woman's allergies.
Cruise 13: Alone again.
The common trend I see is that they paired us with kids of a similar age, and later on put us with other cruisers who were new. And also a lot of times put us alone with our own 4 top.