As soon as a JACK app is started, the automatic quantum change is
disabled. This means no pulse/alsa app can change the quantum.

The only way to change the quantum is with node.force-quantum or
with the settings metadata.

This means only a JACK buffersize change (usually controlled from the
JACK app, such as in ardour) or a metadata change (from the command
line) can modify things. Both of those are usually caused by a user
action.

For JACK apps where the quantum is allowed to change automatically,
explicit rules need to be placed in the config.