What size drying tent?

Drying racks can cause flat buds, and force you to cut your harvest down into smaller sections. This in turn will dry your harvest faster. So it depends on your goals I suppose. It will take at least 3 days just to remove water from the bud, and then start the curing process. The racks can have it drier faster, but that isn’t necessarily a good thing. A quality smoke requires a quality cure. I tried the drying racks - once. But that was my experience with it.

As a fellow perpetual harvester, I imagine you'll also want to confine all tents to a single space... If so, I would def not dry ambiently in the room and would indeed do a tent. Carefully control the humidity and use minimal airflow to keep the tent proper - use an automated controller set up for a drying space if you can swing it. For context on how much is big enough, I have a 4x4 veg space that goes into two separate 2x4 flowering spaces offset by ~1 month. This sounds analogous to what you're setting up. For that I use a 3x3 for hang drying. IMO the racks don't really save much space and the flat spots can be unsightly but if you do opt for racks then get the most tiers possible.

Just make sure the air is moving but don't have a fan directly on them.If you put them in a tent leave the door open.

Drying racks? You want your buds to flatten out? If you hang the whole plant by its rootball you can get away with a 2x2. It should dry in 14 days, giving you ca. 15 days to clean the tent before your next plant is ready.

I dry in the tent I grow in. I just turn the lights off and hang it upside down. I use the extractor fan to vent out excess RH and that's it. Its normally done in 7-10 days then off to trim and cure. If the air is to dry I will run a humidifier outside in the main room the tent pulls air in from. I also like drying whole plants upside down or main branches vs individual nugs or separated buds on a rack. But it works fine for some.

I 100% agree with 00010001 You SHOULDN'T have air flowing around your bud that's not natural. Using a tent you will need to add a unnatural airflow which will dry your weed WAY to fast resulting in BUSKWHACK. (hay smelling weed) Dark room. Or if you can block out the widow. Close the door & turn off the radiator. Between 18-21c 20 been optimal. Hang upside down whole. As the days past. Clip the bigger fan leaves off that are limp. And start trimming sugars holding the stem while doing so. (I see sooo many ppl trimming wet bud with sticky gloves) cringe. They're actually damaging the bud Believe it or not. Drying is 1 of the most important processes. Takes a very long time to get it to your style.

I respectfully disagree with 00110000010010011110. I dry in a tent and have perfect climate control and ample air moving around my plants. It's a key piece to making my dry/cure process so successful. I don't have drying racks, either. I have rows of fencing wire that I have strung across the top, from side to side. I hang the branches or plants from those wires after trimming the fan leaves. However, I am not trying to dissuade you from buying drying racks. I just find it an unnecessary expense. Now, your question of a 2x4 tent being large enough. I have a 2x4 tent and I find it is only good for storing a couple of clone mothers, or occasionally turning a female to a pollen donor. It's also a good space for seedlings, but I find it too small for my purposes. I use 5x5 tents except the one 2x4, as mentioned above.

If you have room for it, get a tent that is the same size as your flowering tent (or one size smaller tent), looking at your journals it looks like you grow in 100cm x100cm and 120cm x 120cm, so a 100cm x 100cm should be fine, and you probably could get away with a 120cm x 60cm tent but it's better to have a bit of wiggle room. I recommend drying whole plants or branches with only the fan leaves removed, it's easier to dry trim and you can do it a little bit at a time, trimming a pound wet all in one go is borderline torture :)

I wouldn't dry in a tent. It's too small of an area, and you have to control the environment of the outer room anyway if it's going to exchange air with it, otherwise the effort to do so in the tent will fail. Any circulation will be too strong, imo. Shouldn't have a breeze going across the buds, it'll just dry it too fast. You want circulation in the room, but it shouldn't impact dry times... merely enough to keep RH consistent rather than heavy in one area. That takes very little wind to accomplish in a small room. I use an old tent frame in a small, cool room with a 60% RH. I wet trim and snip down to bud-sized bits and still get a 10-13 day drying time. Leaving them on the branches, dry-trimming or even hanging entire plants are tools to impact length of drying times. A 36" rack can hold over 1/2 lb in a single layer and well-spaced buds. Believe a 24" rack is just under 1/2 the area, so 1/2 the capacity - 1/4 lb per tier is a safe/conservative estimate. So, a minimum of 4 tiers of a 24" rack, but you should go larger, because it's a very cheap initial cost and last forever if you clean and don't treat them roughly. Maybe you want 1 plant per tier regardless of filling it up. Makes keeping plants separated easy too. If you use HEPA13 air filters in the room, you can even go with the cheapest racks possible that don't have a full mesh covering, not that it can keep out finer dust anyway... an air filter in that room is still wise with the zipper accessed racks.