I guess I have my answer: Not all that well:
Now I've tried darning socks in the past, with limited success. This time I used Cookie A's own instructions for repairing a sock using knitting:
This was certainly my best sock repair yet.
This is how it looks on the inside.
It did make me realise that once I get back to knitting (which will be tonight, and hopefully go well!) I would benefit from knitting Leon more socks right now, otherwise he'll be wearing them out as fast as I make them, and then I'll never reach my goal of Leon having a pair of socks for every day of the month.