Jenkins Pipeline "node inside stage" vs "stage inside node"

With node { stage { ... } } each stage will share the same working folder and all the files from the previous stage will be there for the next stage.

With stage { node { ... } } you need to stash/unstash files between each stage. If you have a large repository, and especially if you have a large folder of dependencies like node_modules, this repeated stash/unstash could end up being a significant, or even majority, or your build time.

IMO I would generally start with the first syntax, node { stage { ... } } as preferred. If you have individual build stages that take time and can benefit from parallelism, then switching to stage { node { ... } } might be better, as long as the time gained in parallelization is not lost in stashing.

Update:

I tested the exact effect of swapping nesting on one of our builds. with a bunch of stages inside a node, the total build time is just over one minute. With a node inside each stage, total build time is almost five minutes. Big difference.

This depends on your actual needs.

As long as you can run your complete pipeline on a single node, I would wrap the stages in a node so that the pipeline is not blocked by busy executors.

As soon as you use the parallel step, then you don't really have a choice besides having stage around node allocations.

There are (at least for me) no issues around mixing that, i.e., have the first 2-3 stages executed on the same node and then one stage that executes on multiple nodes within parallel.