Preference for build or debhelper installing systemd unit files?

[jtc@acorntoolworks.com (J.T. Conklin)]

This question is related to components Dell EMC (my current employer)
are contributing to the Linux Foundation's openswitch project.

With debhelper, systemd unit files can be installed by a package's build
(ie. the Makefile installs them in $DESTDIR/lib/systemd/system/...) or
they can be put in the debian/<package>.service and dh_systemd_* will
copy them to the package.  In both cases, the dh_systemd_* scripts
ensure that the proper boilerplate to enable/disable the service is
added to the package's {post,pre}{inst,rm} scriptlets.

My question, in the case where the same organization/people are
responsible for both the software and the debian packaging, is whether 
there is a preference of which method is used.

    --jtc