Is it necessary to run pg_ctlcluster stop on Ubuntu 16.04 before shutting down?

Question

I haven't run

pg_ctlcluster stop

or

pg_ctl stop

or

sudo systemctl stop [email protected]

before rebooting since I installed Postgres on my Ubuntu 16.04 machine.

I'm wondering if I've been lucky (since I've detected no database problems) or whether an Ubuntu shut down does an orderly shut down of Postgres.