I feel like if I were a network operator for something that sensitive I might send some bursts of traffic to nothing just to keep anyone trying to infer "lots of traffic" → "something going on" on their toes.
(Though certainly things like packet timing, packet size, etc. might make more thorough analyses harder to escape…)
I'm now imagining a significant portion of some small country in politically sensitive area's external internet bandwidth being composed entirely of vpn encrypted email with attached Word docs and Powerpoint decks full of "This page left intentionally blank" sent from embassies back to their respective motherships...
(Though certainly things like packet timing, packet size, etc. might make more thorough analyses harder to escape…)