More detailed scenario what can happen: user clicks an item1 on recyclerview->call to API is added to smth like queue or data stream(if rxjava)->user clicks an item2->call to API is added..and so on. And somewhere it should be an observer which calls API one by one if it is in the queue. Please if you have an idea how to implement it, help me or ask if something is unclear.
You need to sucbscribe on Schedulers.single(). Not at all.