Darkwing was actually hypercompetent at times after "getting dangerous." The show creator (Tad Stones?) said he fucks up when letting his huge ego, selfishness, and self indulgence get in the way. Also, when he's failing to learn whatever moral lesson the episode is trying to teach (it is Disney, after all). But when he learns the lesson and can put his ego aside, he can get things done.
Of course the characterization on this cartoon could be very inconsistent, so there were annoying times he and others just tripped over themselves into winning. But there were also episodes where he won through his ingenuity, quick thinking, and skills. His first defeat of Taurus Bulba comes to mind. You can also see how effective he could be a Darkwarrior Duck if he became single minded about crimefighting.
The first episode with the Fearsome Five showed the paradox. He found the bad guys' hideout from a single crumb of food that he found at the scene. This requires great detective work, the problem is Nehaduck also put up an enormous flag showing where their hideout was that Darkwing didn't notice. Darkwing was so enamoured with the thought of clever detective work, he threw common sense out the window and overlooked the obvious, another one of his many character flaws.
Also remember that unlike Penny, Gosalyn was not in every episode, and had a lot of the same flaws as her Dad, so she caused him trouble sometimes, too. Her friend Honker was in even fewer episodes. Darkwing's biggest problem was his flawed personality.