Although aiming to recreate the original MMO's experience, World of Warcraft Classic does employ some of its modern counterpart's technology. Layering, in particular, has been a cause for concerns for some players, which led to Blizzard releasing a hotfix tackling one of the issues arising with the system.
More specifically, the hotfix in question adds an increasing cooldown when players attempt to rapidly change layers in an attempt to circumvent waiting times for respawning materials or mobs.
World of Warcraft Classic Changing Layers Hotfix
"We recently developed a hotfix that restricts frequent layer-hopping, without impacting those who simply wish to play with their friends.", the developer wrote in a post.
"Now, each time a player moves to a new layer, there will be an increasing amount of time before that player can move to another layer. If a player moves between layers multiple times over a short timeframe, the cooldown can increase to a duration of several minutes (or longer) before they can change layers again. The cooldown will then decrease over time for players who don’t change layers.", it continued.
World of Warcraft Classic uses both sharding and layering from its modern counterpart during its first months. These technologies help provide a smoother experience for players, especially when servers are more crowded, by not dumping the entire population in one instance. Teaming up with friends assigned to a different layer is still possible and remains unaffected by the hotfix, as Blizzard itself mentioned.