Anything 7+ days long is fine, but 'they' say to shoot for longer. In my experience, wet trim and cut down to similarly sized nugs on a mesh rack in 60% rh and mid-60F takes about 9-12 days depending on density of nugs. Whole plant and no trim probably 14 days? Though a strong breeze might hasten that process.
no direct wind.. temp and rh are fine. If there's a strong breeze, it'll speed up the process and cause an even greater difference between evaporation off the surface vs how quickly the moisture traverses the plant material from the center - the outside feeling dry but far from done is exaggerated further. The excess moisture deeper in the plant materia takes longer to 'spread out' than rate of evaporation off the surface. So, it lags behind... therefore buds feel dry before they are actually dried properly.
a small tent is not the best drying space, even though it's commonly used. whatever circulates air almost certainly is causing a too strong breeze over the buds in such a tight space. circulation is only to ensure temp and rh stay consistent throughout the room or tent in this case, if closed. open it up on all three sides or just remove the canvas altogether, imo.
if temp and rh are controlled, you'll quickly learn the timing for however you dry... Keep the climate similar and it'll be much easier to learn how to adjust, if needed. Can further manipulate drying times by hanging branches or cutting down to nugs or wet trimming... all of those options obviously speed up the process and hanging whole plants is the slowest option.