How long can PLA sit in the Qidi Box before it goes off?

You can leave it hands-off, but the trick is to dry the spool properly once before letting the Box maintain it. The Box has a heated drying mode you run with the spool in place, and that's what actually pulls the moisture out. After that, the sealed interior with the desiccant is just holding things steady, not actively removing water. So if your PLA went straight from a fresh-factory-sealed bag into the Box, you're probably fine. If it came off a partially used spool that had been sitting out in that basement room, I'd run a drying cycle before trusting it on a long job, just to reset the baseline. The half-hour open lid thing matters way less than you'd think. PLA picks up moisture slowly compared to nylon or PETG, so half an hour of open lid isn't a disaster. What kills you is repeated open sessions in genuinely damp air with the desiccant already saturated. The Box works like a sponge economy: silica gel keeps the air dry until it's full, then it can't absorb anything more and the damp room gradually wins. Recharge or swap the desiccant now and then and those open lids become a non-issue. Since the whole thing is sitting in a damp basement, the desiccant will saturate faster than it would upstairs in normal house air. An easy habit: if you notice the humidity reading creeping up over a couple of days or evening out near room levels after you close the lid, that's your sign to refresh the gel. You can tell the gel is done when it stops changing color after a recharge too, it just gets lazy and goes orange-less for good. The stringing and popping test you're already doing is exactly right, by the way. Popping or crackle at the nozzle is wet filament, no ambiguity there. If your long jobs come out clean and quiet, the Box is doing its job and you can just keep the lid closed between runs and swap plates whenever.

Follow up on the gel part, because mine came with a few little packets loose in the bottom and I have no idea if that's normal or if they're supposed to sit in some holder. Also mine turned a bit pale after a month, so I chucked them in the oven at low heat for a couple hours like a coworker suggested and they went back to orange, which felt like a win. Does oven recharging work for everyone or did I just get lucky? I left the door cracked and set a timer because I forgot the first time and nearly baked them all afternoon.

I'd push back on the 'open lid for half an hour is no big deal' part. Maybe that's true in a normal room, but this printer sits in a damp basement, and half an hour is plenty of time for that air to swap out inside the box. I keep a spool in my garage over winter and even ten minutes with the door open nudges my little humidity gauge up a few points. The gel can only soak up so much, so why hand it free moisture for nothing? Close the lid when you walk away, it costs you two seconds.