based on my observation in Rudong,Spooner doesnt tend to stay with Red-necked Stint more than the other waders.We often scan a flock of Dunlin and Sandling etc. for Spooner.
and the timing of Spooner's migration and moulting doesnt coincide with that of Red-necked Stint.Instead,it fits better with that of Dunlin etc.
I think it's partly due that some Red-necked Stints are long-range migrants--they go to Australia,while Spooner and Dunlin are just short-range migrants wintering in Asia.
From resightings of color-marked birds eg. Red-necked Stint,birds wintering in Thailand have different timing of migration from those wintering in Australia.Spooner tends to come and go with Thai birds rather than Australian birds.
Great Knots are arriving in Australia now,and in Rudong there're less and less Great Knots while more and more Dunlin&Spooner.