I've been a technician for a while, and before that I built computers in my home. I've done test upon test, and every time no matter the thermal paste.... I've come to find a few things out.
1) Thermal paste is only there to provide a connection, thermally conductive connection, to the heat sink. We all know that thermal paste will NEVER be as thermally conductive as the heat sink itself, so with that in mind, I've always found less is actually more, but always maintaining enough for even FULL coverage of the contact area of the heat sink. (Sometimes the entire CPU is not in contact with the heat sink, in that case, try and limit the paste to just the area that will make contact) BTW the ones that don't use the full contact area of the CPU, are junk!
2) With keeping that less is more, I've found that the thinnest layer of paste across the entire surface to be the best. I use a plastic sticker applicator I sized down to be easily held. With some practice I can do a one swipe pass and get a thin, almost even, layer of thermal paste.
I'm not just using the time I've spent building computer after computer as a technician, but I work in a small shop that takes pride in our builds, and we benchmark every single machine that leaves here. The ones with the lowest temps are the ones that we use the above method on.
We've had other technicians using various other methods, some of which where mentioned here, and less is ALWAYS more, and thin even layer turns out to run the coolest. So take that how you want, I'm just laying out the facts as we've seen them.
Also lapping/buffing/honing the heat sink and CPU surfaces is a VERY inexpensive way to permanently drop 5-10 degrees Celsius, if you can do a precision job, you actually do NOT need thermal paste.
We've created three machines this way, and we even TRIED thermal paste! Every time it added 1-5 degree's depending on the paste. Obviously the precision allows for a perfectly mated surface that doesn't actually have room for thermal paste or it will lose contact with the other side. This method will ALWAYS run the coolest, and the pressure of the heat sink clamps allow it to never move, and will resist the minor warping caused by heat fluctuations in metal.