I remember lapping my big copper thermalright cooler for my athlon xp 2500 back in the day and got stable at almost twice its rated clocks on air, I won the silicon lottery with that chip and never even needed to mod it with a lead pencil
I was fresh out of high school and into university back then, so no real disposable income. But I'm that kind of guy. I just had to do it. It was risky and I was scared as hell of breaking it. But there was simply no realistic scenario in which I didn't take that chip and lapped the crap out of it. It's too exciting for me. But I'm happiest when the stakes are high or when something breaks and I have to figure out how to fix it.
It's both nowadays. First you delid and then you lap the chip. But back then almost nobody tried to delid their CPU. It was mostly about lapping the IHS. It means that you're polishing the surface to a mirror sheen. You can find old tutorials about it on YouTube.