Cattleyas - How Dry is Dry?

[mopwr]

I've been growing and blooming orchids of all types for a while, but my weakest point is growing / blooming cattleyas. I'm not saying I'm bad at it, per say, but I am always trying to do better. I have grown and bloomed plenty of cattleya hybrids and some of the less fussier species, but they never quite look as robust as I see from some other growers.

I grow intermediate / warm cattleyas (Aclandiae, Nobilior, Amethystoglossa, Rex) under lights, in a large terrarium setup where I can control for temps and humidity. I keep the temp and humidity ranges where the plants should like them, summer 84F day / 68F night and winter 78F day / 62F night (humidity around 70-80% year round). As far as light goes, I give them the higher end of the range they should like (based on a par meter). So with all of that, I'd think they'd be set.

Going back to the question in the title, I'm beginning to question my watering regime, how dry is dry enough? The reason I ask, is that I've seen growers that have cattleyas sitting in what looks desert dry bark, and then I see cattleyas growing with moss completely covering the bark. I always try to get mine fairly dry, though not necessarily dry to the core if I were to unpot it, but... they definitely get dry enough that moss would never really take hold. Given my current humidity and temps, it might take 7-8 days for them to get bone dry, I probably water every 5-6 days when in active growth.

To complicate things, I have a couple of cattleyas in semi hydro which basically stay wet all the time, year round, and are doing great, including Dowiana and Perciviliana and I'm always curious why they need to dry out in bark, but can stay wet all the time in leca. I even bought a Warscewiczii from orchidweb that came in a plastic pot with pure sphagnum, which doesn't make sense to me at all - as soon as the new growth pushes roots, I intend on repotting that one.