Overnight prints: worth the risk or just asking for trouble?

I always run longer jobs, usually eight to ten hours, though I never let them go past the middle of the night. My Ender 3 V2 has been reliable, but I've seen failures come down to environmental stuff, not just the slicer settings. The biggest issue for me isn't the print head crashing; it's poor layer adhesion leading to massive string buildup when the print stops. If I'm doing a complex print with a lot of overhang, I usually raise my retraction distance a bit beyond what the default profile suggests, maybe by half a millimetre. It might sound fiddly, but it keeps those little wisps of filament from solidifying and clogging the nozzle before I get up in the morning. My rule is that if I’m doing anything critical, I’ll run the first five layers manually and then set a notification on my phone for when it hits about five inches high. That way, I know it’s progressing correctly before I commit to a solid twelve-hour run. Most of the times, though, the setup is stable enough that I just let it run and check in on it first thing after breakfast. It's about minimizing risk, not eliminating it entirely.

I tend to push these thing for much longer than most people suggest. I have a heavy job scheduled every couple of weeks that runs for nearly fourteen hours straight, ussually starting mid-afternoon. My printer is a working machine for me, and if the setup is right, I don't see the point in stopping halfway through a complicated build just because of a clock. My rule is that before I ever turn the power off, I spent a good thirty minutes calibrating the temprature and flow rate. Specifically, I watch the first two layers on the build plate to confirm the extrusion looks uniform and solid. If those layers are consistent and there's no obvious clumping, I'm comfortable leaving it going untill the final layer finishes.

It feels less about timing and more about maintenace. The printer itself is the system I need to trust, and for my setup, I find that if the initial calibration is solid, the machine just keeps performing its function. I don't really worry about the wires or the plastic building up inside the nozzle if the flow is correct.

The one blob that ever happened to me wasn't a slicer problem at all. My filament spool had a loop tucked under itself, and about four hours in it snagged hard enough to drag the print off the bed. Now I spool off a foot or two by hand before a long run and hang the roll where it can spin free. Cheap fix, zero failures since. Also I stopped trusting a first layer I only glanced at. I sit there through two full layers now, boring as it is, because every failure I've had showed itself right there.

For me it was a cheap wifi camera pointed at the bed. I used to do the wake-up-at-3am-and-check thing, which defeats the purpose of an overnight print. Now I keep my phone by the pillow and if I stir, one glance tells me if it's still laying down layers or grinding into air. The other half of it is a smart plug on the printer, so if the camera ever shows somethig ugly I can kill power from bed instead of sprinting down the hall. Haven't had a blob since I started that setup, though I've caught two prints early enough to save the job. Do you have any way to see the machine from where you sleep?

I'm still too nervous to do the whole night thing, partly because my situation is a bit diffrent. I live somewhere where the power blinks off for a few seconds every couple weeks, so even a perfect print can get killed by something I can't control. No camera or spool trick fixes that. So for now I only start anything that can finish before I need to leave the house. Does anyone here use something that resumes a print after a power cut, or does that usually end badly anyway? I honestly don't know if trusting that feature is brave or dumb.

Gotta push back on the retraction advice. Bumping retraction up past what your profile calls for doesn't stop blobs, it usually makes things worse. Too much retraction and you pull air gaps into the nozzle, then heat creep sets in and you get a clog mid-print, which is exactly the overnight failure you're trying to avoid. Stringing looks ugly but it doesn't kill prints. What kills them is the part coming loose or a shift, and no slicer tweak fixes either. I'd rather leave retraction stock and spend the time making sure the bed is actually clean and the part is anchored before I walk away.