Adapt Dockerfile best practices

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Currently the Dockerfile only has the OS dependencies and a git clone from the GZDooM repository.
Compiling is done in a separate script in the ephemeral container.

Should the compiling process go to the Dockerfile too? What's the recommended practice? I tried to research this but unable to find a clear consensus. Docker does save intermediary stages after each command it runs. So in practice everything could go in the Dockerfile as changes only affect the commands after the change, i.e. the image is not built from scratch every time.

I've seen people do this both ways and I don't know which one is the best practice.