Axel wrote: ....Right now I see preview rendering as completely useless (also read the "lost renders" thread!). Currently favor a native & proxy workflow. But it all depends....
I usually don't pre-render, and it's normally not necessary. However there are cases where it makes a major improvement.
E.g, a complex timeline and you are late in the edit phase and must export multiple proof copies for final approval while making the last few tweaks. Typically a deadline is looming. In this case doing a pre-render can really speed things up.
I just tested a complex 4:30 documentary I worked on which had hundreds of edits and effects. On my 10-core Vega 64 iMac Pro it took 15 min to export it as 4k H264 "fast", but after pre-rendering only took 02:42, or about 6x faster.
If you are only exporting once, pre-rendering doesn't help. But if the so-called "final" version ends up requiring 10 or 15 more small changes (each with an export) before approval, it makes a huge difference.
Re the "lost renders", I've seen that periodically but in my recent tests on 10.4.4, macOS 10.14.2 and Pro Video Formats 2.0.7, I rarely see it.
I wonder if some of those cases are people using an adjustment layer. If that gets bumped by even one frame the entire timeline must be re-rendered.
joema wrote: If you are only exporting once, pre-rendering doesn't help. But if the so-called "final" version ends up requiring 10 or 15 more small changes (each with an export) before approval, it makes a huge difference.
There you have it: it all depends. I am never particularly pressed for time, and I feel no urgency to evaluate export times with a stop watch. To me as well render all and export without pre-rendering seem to be reasonably fast. Had a sequence of very short cuts in native UHD recently, and playback wasn't perfectly smooth. Since during editing timing-feedback is paramount, I had then created proxies after the fact, and that made the difference. Old news of course, but I had always said, I don't need proxy with FCP X.
joema wrote: Re the "lost renders", I've seen that periodically but in my recent tests on 10.4.4, macOS 10.14.2 and Pro Video Formats 2.0.7, I rarely see it.
Had extensively tested a multi-step color workflow and wanted to show off my colors to a friend. He said, I'll buy cake and come by in ten minutes. Render all of a complicated timeline was long done by then. However, although I had just played back the timeline and hadn't changed anything, after the next launch the whole timeline showed up as ...........
The general opinion on this bug-like behavior seems to be, well, yes, it's a nuisance, but no dealbreaker. If someone with really big projects like you still feels comfortable with it, why should I complain?
I almost never render anything so this isn't a big issue for me. But, I wonder if FCPX is set to background rendering on (which I do not recommend) would make a difference with projects retaining their render files. I'll try that later to see if the quirk is somehow associated with that preference setting.