I've got an animation I've rendered that looks pretty good, with exception of a subtle flicker in the highlights.
Unfortunately I can't share an example as the work I'm doing is under an NDA but I'll try to explain it as detailed as possible.
I've got an interior setting, an airline cabin to be specific, and a camera panning through the rows of seats. Imagine walking down the aisle with the camera facing the wall and windows. I'm happy with the lighting, shadows, and so on, but frame to frame, there's a subtle variation in lighting among the highlights, mostly where the light streams in through the windows and on the glossy plastic surfaces. It's as if each frame has been calculated slightly differently. I at first thought it was a case of video compression, but I can see it even with no compression.
Most of the lighting is coming through the windows with an HDR outside, it is cranked up to 30 for the strength which gives me the look I'm going for. There are interior lights as well above each seat.
One unusual thing I'm doing is using the filmic log encoding base, it's a set of colour settings I've installed from here: https://sobotka.github.io/filmic-blender/
The result in my opinion is far superior contrast in my aviation renders given the nature of intense bright light coming through small windows.
I'm rendering in cycles, GPU, with 600 samples and a max noise threshold of 0.01. I've seen noise issues when I reduce this setting so I've left it pretty high.
Do I need to change other settings? These 200 frames take about 8 hours to render, so I haven't been willing to spend too much time experimenting.