In northern Minnesota the humidity can vary greatly. Last weekend it was 90+% outside. While indoors the air conditioning had the house around 50%. And by winter time, the outdoor humidity can be as low 20% and indoors depending on heat source, around 30% to 40%.

I finally broke down and bought a dedicated filament dryer, Sunlu S2, because my trusty old food dehydrator died the week before. I do dry PETG when it tells me to, and I always dry TPU. But never PLA.

Just for fun, after I was done drying and printing some PETG, I dropped a mostly used spool of Sunlu white PLA into the dryer, (first time ever for PLA). That spool has been laying around in the open for at least 6 months now. The humidistat on the dryer showed 30%. I let it dry down to 20% and ran a test cube. No difference in print quality that I can see.