Its prefered, to keep a fresh air flow. Some T's do better with cross ventilation (like avics)Is cross ventilation always needed for tarantula enclosures?
Sorry, not sure on specific genus, I'm fairly new to the hobby myself.Just to be more specific, would top ventilation be sufficient for any species in the Theraphosa, Cyriopagopus, and/or Chilobrachys genera?
And Dave's Little BeastiesYou should check out YouTube. I'm sure Tom's Big Spiders (Tom Moran) will have a guide on those specific species. You can also try The Tarantula Collective and The Dark Den.