A 4-hour render that sleeps at hour 3
You kick off a long export in Final Cut Pro, queue up a batch encode in Handbrake, or start a Blender render that's going to take the rest of the afternoon. You leave the room. Three hours in, your Mac decides you're idle and goes to sleep. The render stops. When you wake the Mac up, some apps can resume where they left off. Others can't. And even the ones that can resume have to re-initialize the GPU and rebuild their processing pipeline, which adds time and sometimes introduces errors.
You'd think rendering apps would tell macOS to stay awake. Some do. Compressor usually handles this correctly. But Final Cut Pro, DaVinci Resolve, Blender, and Handbrake don't always request sleep assertions, especially during exports or background renders. If the app doesn't explicitly tell macOS "I'm busy, don't sleep," the idle timer keeps ticking and your Mac will sleep on schedule.
CPU threshold: auto-detect when you're rendering
Shake It On has a condition called "Only Shake If CPU usage above threshold." Set it to something like 20-30%, and Shake It On will automatically activate whenever your Mac is doing heavy work. A video encode that's pinning your CPU at 85%? Shaking is on. The render finishes and CPU drops back to 3%? Shaking stops and your Mac can sleep normally.
This is the perfect condition for rendering because you don't have to think about it. You don't need to remember to enable anything before you start the render, and you don't need to remember to disable it after. The CPU threshold does the thinking for you.
For most rendering workloads, 20-30% is the right threshold. Video encodes and 3D renders typically push CPU well above 50%, so there's plenty of headroom above the trigger point. Normal background activity (email, browsing, Spotlight indexing) rarely sustains above 15-20%, so you won't get false positives.
Pairing conditions for overnight renders
If you're starting a render before you leave for the day, you'll want a couple of extra conditions:
- Paused When on battery. If you're rendering on a MacBook, you're almost certainly plugged in. But if someone accidentally unplugs the power cable, you don't want Shake It On keeping the Mac awake on battery while the CPU is pegged at 100%. The battery would drain in no time. This condition catches that edge case.
- Allow display to sleep. An overnight render doesn't need the screen on. Let the display turn off to save energy while the system stays awake and the render continues.
With the CPU threshold, battery pause, and display sleep all configured, you get exactly the behavior you want: Mac stays awake while rendering, display goes dark to save power, and everything returns to normal when the job finishes.