This particular SK is somewhat confusing. I have dealt with it on several occasions. The SK is marked for R81.10 and R81.20, and the content makes it seem like the FWK Thread Blocker is enabled by default on both R81.10 and R81.20, which is not the case. It's enabled by default on R81.10. The feature has been disabled on R81.20. I have ended up following the SK needlessly on several installations as a result of this.
I have verified this on multiple installations.
Certifications: CCSA, CCSE, CCSM, CCSM ELITE, CCTA, CCTE, CCVS, CCME