I see no logical way to make 300% return in 20 trading days, unless there was another "black swan" or "black thursday" that favours your position. The truth is most of us will probably OVERTRADE.
300% in 20 days? Does not need a black swan event at all. Hard yes, very risky yes, prone to blow up, yes, but by no means a black swan requiring feat. It's 'only' 7.5% per day, compounded -- Returns are not that predictable or consistent in reality of course, but the point is, 7.5% per day for 20 days, in aggregate, is not that inconceivable.
To explore this a bit more: 7.5% in one day only requires for example catching, every day, a single trade capturing a...
7.5% move at 1:1 (= no!!!) leverage (!)
3.75% move at 2:1 leverage (pretty low leverage still)
1.875% move at 4:1 leverage
0.9375% move at 8:1 leverage (leverage getting high)
Now that's only one trade -- consider that you're probably going to place more than one trade a day (a couple, not overtrade per se), which would allow you to further keep your trade size/leverage in check, finally consider that some securities (crude oil) for example rarely move less than 2% in a day (lately usually about 5% on a typical day and sometimes as much as 10%), then you can start to see that it's actually not that inconceivable to return 7.5% a day for 20 days in aggregate (=325% total net return). So: Would it be hard? Yes. But does it require a black swan event? Not really IMHO. :)
edit: Sorry had the math slightly wrong originally so redid it (I originally reported 300% gross return = 200% net, which takes about 5.7% compounded to achieve.)