Power Overhaul

Most of the time in media, people gradually adapt to their new abilities, whether these are supernatural or not. It's not uncommon to get drama and chuckles out of a hero figuring out "How Do I Shot Web?". However; occasionally you have a sudden change in powers accompanied by someone becoming insanely competent in their use.

Much like Possession Implies Mastery, a character becomes an expert in their new power or school of magic as soon as he gets it. Almost as if it were a computer program he just installed. A character previously seen only ever swinging a sword around suddenly dons a robe, loses the sword, and starts throwing around the battle magic, while a character who never got in a fight before and has some prophetic powers suddenly becomes some sort of martial god. Villains generally tend to be much more competent with new powers than heroes.

This has the potential to be done poorly and become infuriating; however, it can be done well, assuming that there is actually a reason for something like this to happen.

Anime and Manga

 * Bleach has this when Ichigo gets Fullbring abilities. Not only does he beat up a fully fledged fullbring user within his second Fullbring fight, but also was able to instantaneously observe the weaknesses of his abilities and compensate for it.

Film

 * In the movie Surf Ninjas, the two main characters are two surfing elementary-middle schoolers. One becomes insanely gifted in martial arts as soon as he gets into a fist fight, while the other learns how to predict the future via an handheld console: both of these happen after they are told they're princes of a faraway island and that they should be able to hold such powers. The fact that they immediately learn how to control their power is played for the laughs, but it's one of the many illogical points of the movie.

Live Action TV

 * Justified with Sylar from Heroes, whose original superpower was understanding how things work, so he can pretty much instantly master any power he steals.
 * Arthur also seemed to gain perfect control over every power he stole, even the ones like Hiro's that took a long time to use properly. Although this is more due to his firm status as a Villain Sue more than any real justification.
 * Possibly justified by the common mechanism for all powers in the series which is seated in the adrenal gland and is emotion triggered. His previous experience stealing powers could have given him a good feel for how powers work in general in his world whereas the people shown previously struggling with their powers didn't know anything about the larger world of superpowered people when they first got them.
 * After the main cast of Misfits, they're shown having a much finer control over their new powers  . Somewhat justified by the fact that the original powers were rooted in anxieties and subconscious thought, so getting rid of the baggage (or not having it in the first place) lead to more control.