I'm editing in a 1080 timeline @ 24FPS. I'm using 8mm film grain & matte overlays of varying frame rates e.g. 23.98, 25 & 60FPS. I'm wondering if there is a rule of thumb for using varying frame rate overlays in a 24 FPS timeline or should I use "automatic speed" retiming on the overlays?
If it's an effect overlay, I'd not sweat it until I had a problem. If you're worried, convert them to the proper frame rate in Compressor, perhaps. But personally, I'd just move forward and not sweat it.