Yes, segs or 'quarter tips' as I knew them where actually inserted in the the edge of the sole after removing a bit of it - usually by a professional cobbler. They are probably still used to preserve leather soles.
Quarter tipped brogues or loafers from Shelley's were impossibly cool. I had plastic charity shop brogues, and to add insult to injury, when I asked my mum to get me some blakeys, she managed to get me rubber ones which I had to hammer in with little nails. The nails afforded some percussion when walking through the playground after morning lineup, but nothing like blakey's or proper quarter tips.