Hi Erik, they are not random, they refer to the operation we are trying to test in the example

Observable.interval(1L, 5L, TimeUnit.SECONDS, getSchedulerIo())
            .flatMapSingle(ignored -> fetchDataRemote())

Expected behaviour here is: we wait 1 second first, then we fetch data from remote, then we fetch data again and again after every 5 seconds

Does that answer your question?