Run the code (with some debug logging statements, very likely), find a small mistake, make a few characters worth of correction, press your IDE's keyboard shortcut for recompilation and re-running.
If the last step is slow you can lose momentum and motivation to iterate quickly on the problem at hand.
Sure it doesn't apply to a lot of projects, that's true. But it's not charitable to claim it only applies when learning.
it depends on the problem domain. when working on say a desktop app with graphical ui features it can be very useful to be able to change/experiment quickly.
with an n tier web application you wont often be able to do that anyway.