<aside> <img src="/icons/info-alternate_gray.svg" alt="/icons/info-alternate_gray.svg" width="40px" /> Depth of friendship ∝ Time spent willingly × Sharing
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My observation is that nothing else matters as much as these two factors.
P.S. I got the idea of sharing being a major factor from Srikanth Thunga (whose blog doesn’t seem to be alive any more).