I don't have great ventilation, I have no ventilation. You turn off the exhaust fans in a sealed room. Once every 2-3 hours during lights on I turn on the exhaust fan for a few minutes to recirculate fresh air.
I have also read about different strains performing better in different environments, I can see that. When people breed landrace strains around the world, they select the best performing ones in their environment, which breeds plants that favor conditions in a specific local region.
Most people following the VPD chart would say that operating below 50% RH is too high of a VPD and too stressful to the plants in any stage beyond late flower. Not sure why you are saying it is unnecessary if that is the recommendation of countless experts for optimal parameters. I doubt you are pulling 3+ pounds per light using that growing style, maybe you are hurting your yields by a dry environment. Why do you run at a high VPD? There are other ways to combat mold like the ProGuard. What benefits have you found from lower humidity besides avoiding mold?
People who buy the ProGuard supposedly never get mold and pass all the microbial testing.
https://craft-farmer.com/products/in...-dxm-100-w-mci
Humidity and temp need to be looked at together. Ambient temps aren't the only factor, you need to look at leaf temp. Depending on your lighting technology, that would change ambient temperature suggestions, higher for LED as there is less radiant heat. LEDs need hotter rooms.
Keeping temp and RH% down in flowering in a sealed room can be easily accomplished with a properly sized mini split A/C and industrial dehumidifier.
I turn down exhaust duty cycle and use a space heater to adjust night time temps up/down if needed.
I have tons of sources I can share I've come across in my research that would suggest your rooms are much too dry and your VPD is too high.