I discovered the "s" key more or less by accident. Since I learned that you actually can single-step, I've used it a few times, but most of the time it's not necessary.

Compare this to another project I've been working on which is written in Kotlin. Almost every debugging session involves a lot of single-stepping.

There is no insightful point of this reply, except for agreeing that Lisp is powerful enough that single-stepping is mostly pointless. I do add a lot of (break) statements during debugging though.