Perhaps this is my misunderstanding but I assumed that if I enabled "Log Deprecated API" then I would quickly get a log of all deprecated code as I navigate the site. This would enable me to check to see if any extension not explicitly marked as J4 compatible could be safely used on J4 (not using deprecated api) or could be easily edited to be used on j4 (updating the code whenever it was using deprecated code)

This only happens (afaict) if there is a specific code to add a log eg

	/**
	 * Refresh the list of include paths
	 *
	 * @return  self
	 *
	 * @since   3.2
	 *
	 * @deprecated  3.5  Use FileLayout::clearIncludePaths()
	 */
	protected function refreshIncludePaths()
	{
		// Log usage of deprecated function
		\JLog::add(__METHOD__ . '() is deprecated, use FileLayout::clearIncludePaths() instead.', \JLog::WARNING, 'deprecated');

		$this->clearIncludePaths();

		return $this;
	}

However in a few (important) cases there is no logging at all just a comment in the code. How is anyone supposed to know the code is deprecated in this case? Are we expected to read every line of code?

	/**
	 * Is site interface?
	 *
	 * @return  boolean  True if this application is site.
	 *
	 * @since       3.2
	 * @deprecated  4.0 Use isClient('site') instead.
	 */
	public function isSite()
	{
		return $this->isClient('site');
	}