1:33:02 - IOC -- there's a wide variety of tells... On old flip phones you knew it was tapped when there was a delay and a click before the ring.
... Just because your phone or your computer isn't processing something quickly enough doesn't necessarily mean that it's compromised. (Obviously) 🙄
Note: Targets don't always have to even leave their house but when they do, it's nice to time it out so they can see who's seeing them... Like going on a walk at night and crossing in front of a person's fence light sensor so you can see who's riding on the bike passing you by. (It's probably harder than it sounds) Double backing, going on a different path than their normal routine is a way to spot a tail. (Insert entirely redacted rant here)
Being able to spot sophisticated surveillance is actually easier than "bumbling" surveillance.