It's important to keep in mind
why we use thermal paste to begin with. Thermal paste isn't some magical heat transfer medium; it's actually worse than the metals in your heatsink. That's the reason why using too much thermal paste in that link posted above caused an increase in temperatures. The point of thermal paste is to make up for imperfections in manufacturing (the metal on your heatsink will not be perfectly flat). If you read some heatsink reviews, you tend to see them look for "mirror shines" on the bottom, but it's not because they needed to fix their hair. A mirror shine usually indicates that
lapping or smoothing was part of the manufacturing process.
So, in short, you want enough thermal paste to fill in any imperfections in the metal to avoid any air gaps, but if you put too much, you're going to hinder the heat transfer.