Brad Touesnard shares why you should use WP_DEBUG_LOG in your development environment.
He gives three reason, but the one I never would’ve thought of is regarding plugin load order and how that could allow tools like Query Monitor to miss some things.
Maybe you like to use plugins like Debug Bar or Query Monitor to capture errors and are happy with that. I don’t blame you. Those plugins are awesome.
However, I’ve found that they miss some errors. I suspect this is because they are plugins and other plugins may get loaded before them. I suppose you could change the load order so they load first, but then what about errors in MU plugins and WordPress core itself? Also, last I checked, Strict Standards errors weren’t picked up by these plugins.
I also like using a log file versus when I pull down a client site I inherit. Often times the notices and warnings are overwhelming when they are displayed.