How much thermal paste and how much does the cooler have to be screwed on?

I have two exactly the same laptops from 2014 that I want to get the best possible performance out of.

In the Cinebench 15 benchmark, I always have a 20 point difference. On one laptop I tried to apply the paste very thinly and only tightened the cooler loosely. On the other laptop, a little more paste was used and the cooler screwed on a little stronger.

Does it even make any difference in the amount of paste? How do I get the lowest temperatures and how much must the cooler be tightened to reach the lowest temperature?

As little thermal paste as possible and as much as necessary. (Thermal paste doesn't conduct heat really well)

If it cracks, then you've tightened the cooler too tight

The only option I see is to increase the surface area of the cooler so that there's a larger exchange area between the cooler and air