Why use make -j$(nproc) when calling make

When you run make from the shell, use all your CPU cores so builds finish faster:

make -j$(nproc)

Faster builds

• -j N tells make to run up to N jobs at the same time instead of one after another.
• $(nproc) is the number of (logical) CPUs on your machine, so you don’t have to pick a number.
• On multi-core systems, that parallelism can cut build time a lot when there are many independent targets (e.g. compiling many object files).

Golang

• if your target is to compile golang you can also force golang to use all cores:

ship:
    CGO_ENABLED=0 go build -p "$$(nproc)" -o app

Safe default

• Make still obeys dependencies: a target only runs when its prerequisites are done.
• Plain make (no -j) runs a single job at a time—correct but often slower than necessary.
• Using all cores is a good default; use -j1 only when you need to (e.g. to avoid flaky parallel builds or reduce load).

Summary

Use: make -j$(nproc)
Avoid as default: make (single-threaded) unless you have a reason.