Should I save in 422 for future uses of the video in other videos

I agree with Tom.

You may not notice a difference between 8-bit H.264 and 10-bit ProRes but that does not mean that there is no difference. You may not even notice a difference when you re-edit but then again you might. Much depends on the content. Try shooting a plain blue sky and use the Hue-Saturation curves in FCP. You will very likely see a big difference. Skin tones as well. 10-bit is certainly superior to 8-bit in many cases for smooth gradations in facial skin tones and re-editing 8-bit exports may make this a lot more obvious.

It may not be important for the type of material you are shooting but then again it might. If it is important, you could be making a big mistake archiving in H.264 - all the time you spent editing .....

Of course much depends on what codec you are shooting in. If you are not shooting in 10-bit or higher, the gains may not be so great at all.

You will almost certainly find there is no noticeable difference whether you save as H.264 or ProRes except for a massive difference in file sizes.

To see whether my comments are BS or pearls of wisdom do a test now . . . export a short project as both H.264 and ProRes and then re-edit both.

Compare the two versions. Maybe you will see a difference in quality but it's highly likely you won't. What you will notice is less of your HDD filled.

The only gain is you preserve the original more exactly, so any further processing will produce less degradation from the original than going through multiple cycles of H.264.

ProRes 422 is a good mastering format but it depends on what the frame resolution is. You perhaps should use HQ to master.

Check out the White Paper for a dive into ProRes.

Page 14 may be of special interest to you:

https://www.apple.com/in/final-cut-pro/docs/Apple_ProRes.pdf

Al

Remember that saving an H.264 file as a ProRes (any flavor) will NOT gain you any image quality at all. You'll end up with the same video, just in a larger file size. It's a waste to convert H.264 (which in today's world is a very sophisticated and good quality codec) to ProRes. You gain zero.

H.264 compression has evolved past that, and again, ProRes gains zero, you only have data that is in the original, you can't add to that. It is not "more exactly" anything, it is the original, that's all. Many years ago, that was not the case, but today, it's fine. And who does lots of multigenerational encodings anyway? Normally you ingest, you export, that's it, not enough for any codec to be degraded significantly.

You probably won’t see a difference, though the content is a large factor and will affect the processing. The real problem is when you want to reprocess the media, new versions, recuts, you will likely see differences from the original.

Cassette tapes are a completely different ball game.

They are analogue and as such suffer obvious degradation with each new generated copy but digital is different.

There is degradation but it is minuscule compared to analogue and under most circumstances will be unnoticeable even when pixel-peeping.

Just do the test I outlined in full and decide for yourself.

That's why I suggested re-editing the 2 exported versions and checking the results.

Unless you originally record the footage as ProRes, converting to ProRes afterward gains you zero, simple fact explained to me by an Apple engineer.

If you going to pick a lossy video why don’t you pick H.265? Way better.