I've noticed that lately Hots has been doing a lot of 'one character at a time' releases but for a while they did the 'Here are the next 3-4 heroes' kind of release styles. Personally I prefer the 3-4 heroes style as I would get hyped waiting for Greymane or Lunara to be released rather than not knowing what was next like right now, we just got Tracer and there is no clue which hero could be next.