One chestnut from my history in lottery game development:
While our security staff was incredibly tight and did a generally good job, oftentimes levels of paranoia were off the charts.
Once they went around hot gluing shut all of the “unnecessary” USB ports in our PCs under the premise of mitigating data theft via thumb drive, while ignoring that we were all Internet-connected and VPNs are a thing, also that every machine had a RW optical drive.
What I really love is mandatory length and character password policies so complex that together with such password change requirements that push people beyond what is humanly possible to memorize, so it all ends down written in post-its, the IT equivalent of having a spare key under a vase or the rug.