I think the "compleat" programmer can move freely between the two extremes. I have one piece of code -- in Common Lisp! -- that I've been working on for a coup

I think the "compleat" programmer can move freely between the two extremes. I have one piece of code -- in Common Lisp! -- that I've been working on for a couple of months of weekends and still haven't tried to run (except for an occasional one-line experiment to check that I have the correct syntax for a macro). But I can also adopt a much more interactive, experimental approach in situations where experiments are cheap and easy. It all depends on the nature of the task.