Conditional tags

Hi a question I have always had about conditional tags is do they require the else function?

So some example code might look like this:

if ( is_page_template('about.php') ) {
	// Returns true when 'about.php' is being used.
} else {
	// Returns false when 'about.php' is not being used.
}

But could I get away with removing the else part and just keep if. Would this cause any issues?

if ( is_page_template('about.php') ) {
	// Returns true when 'about.php' is being used.
}

I have tried searching for the answer to this but examples always seem to have else included.