> use a Makefile instead

I was making a general comment that your build should be a single 'command'. Personally, I don't care what the command is, only that it should be a) one command, and b) 100% runnable on a dev box or a server. If you use make, you'll soon end up writing... shell scripts, so just use a shell script.

In an ideal world your topmost command would be a build tool:

     ./gradlew build
     bazel build //...
     make debug
     cmake --workflow --preset

All the cruft that ends up *in CI config*, should be under version control, and inside your single command, so you can debug locally.

That's exactly why the "main" should be shell, not make (see my sibling reply). So when someone needs to add that step, it becomes:

    #!/bin/sh

    step-I-added-to-shell-rather-than-CI-yaml
    make debug  # or cmake, bazel

In general, a CI is not a DAG, and not completely parallel -- but it often contains DAGs