The Blitz:

Although night air defence was causing greater concern before the war, it was not at the forefront of RAF planning. Most of the resources went into planning for daylight fighter defences. The difficulty RAF bombers had navigating in darkness, led the British to believe German bombers would suffer the same problems and would be unable to reach and identify their targets. There was also a mentality in all air forces that, if they could carry out effective operations by day, night missions and their disadvantages could be avoided.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What did the Air Force believe they could avoid if they carried out effective day missions?
night missions and their disadvantages