Like most things, people exaggerate.
At a fund-level, for early stage investing, 2x net of fees is “good enough” to earn another fund, and 3x net of fees is top tier.
The very, very best funds do 8-10x net (sometimes much higher in tiny funds), but even then, often the following funds revert a bit to the mean.
So, it turns out what a top portfolio investment is … is pretty simple. It’s one that “returns the fund” — in profits. 100% of the size of the fund in gains. Then you are half-way to 2x. I.e., an investment that returns $100m in profits to a $100m fund is a big, big deal. Then you are in the money.
Any investment that returns >=10% of the fund in profits is still material to the fund.
Less than 10% is immaterial.