seen the reality TV show "The Hunted"? Burner phones are useless once you use them. They can track the phone# through your friends, family and associates. Then track you. The only way they would work is to use it once and toss it.

one use, for $5 -$10, worth it for some piece of mind for the activist

I think the idea is to not have any info like family and friends' numbers on it. I wouldnt say theyre useless but if you're caught with one....

is get the call records for friends, family and associates. They are then scoured for unknown numbers that suddenly appear. Next they find out who owns those numbers. If a burner cell # comes up, they trace it. If you use a burner for more than 1 phone call it is useless.

I've started using ProtonMail for my more "opinionated" emails. It's encrypted on my end, and it's also possible to require the recipient to enter a one-time-use password to read, even if they're not using ProtonMail themselves.