Pea size is likely too large. I would go more with 'size of 2 grains of rice'.
If you look at an actual pea, they're quite large compared with the amount of thermal compound you want to apply. With large CPUs like Threadripper, multiple rice-grain spots and even some diagonal lines can be recommended.
I like this test from Puget Systems...shows all sorts of methods and their results...which are nearly identical.
https://www.pugetsystems.com/labs/articles/Thermal-Paste-Application-Techniques-170/
And GamersNexus did one on Threadripper, specifically:
https://www.gamersnexus.net/guides/...-thermalpaste-application-methods-benchmarked