plan for Nerofest:

>do ALL missions once to get the guaranteed rewards
>check chart (http://fate-go.cirnopedia.org/quest_event_20150916.php#nav) and look on the bottom of each mission; that's the random rewards you can get (note that they have shit like 33% drop rates instead of fucking 2%)
>farm the fuck out of the ones you need
>use medals to clean out the shop for the rare materials like Homo Babies and so on

>Preliminaries, Semifinals and Finals gives the same amount of medals
>farm bronzes on 5AP, silver on 10AP. Don't worry for the golds since on Finals there's an extra stage specifically for farming it which yield a shitton
>to clear the shop; you need: 300 bronze, 400 silver, and 1100 gold medals.
>tl;dr: farm for the bare minimum of bronzes and silvers, then fuck off to grind for your desired mats drops, if in finals you still haven't cleared the shop you know what to do

Bonus round:

>set up your EXP on the days before Nerofest so that you only need a tiny bit of EXP to level up, thus allowing you to start the day with full AP plus overflow