i think so:
that’s inversely proportional to how close to 50% your win-rate is
with a win-rate of 50%, 100 will be a good enough sample-size, in principle
but statistically speaking, 60/40 is nowhere near 50/50 and will need more than 300 samples to be even reasonably “significant”
but even more important than this, is the point Greg made, above, about different types of market conditions …
example: if you’re looking at a trend-following method, and the period over which you look (for however many days/weeks/months) was a trending market, then the results will be good whether you look at 30 or 300 or 3,000 or 30,000 trades, but if you then try to use the system and the market stops trending and starts ranging (as they so often do!) then you will still probably have a disaster, regardless of the number of trades you checked up on
“robustness” is not about numbers alone - it has qualitative considerations as well as quantitative …
… just to make it even more difficult than it already is! 
