Horizontal space is free, vertical space is not.<p>The more lines that are visible on your screen, the less you have to keep in your working memory. Human memory is fragile, so you really don&#x27;t want to rely on it.<p>I can only fit 51 lines vertically (damn widescreen laptop) so that one snippet fills a good 1&#x2F;3 of my screen.<p>Personally I&#x27;d write that as<p><pre><code>    if (condition_a) {
        if (condition_b) do_thing_a();
        else do_thing_b();
    }
    else {
        do_something_else();
    }</code></pre>