It really depends on context. The first ever lifetime
portrait of
Julius Caesar is on a middle bronze of Lampsacus that dates from 45 BC and is impeccable and realistic, certainly better than most of
his lifetime
portrait denarii which cost so much. On the other hand there is a common bronze issued in the time of
Domitian which features "
portraits" of
Octavian and
Julius Caesar that are, at best, approximately generic male heads. It's coins such as these that give
provincials a sometimes bad name. They were just too far away in both time and distance to be remotely authentic effigies. That doesn't tend to happen as often with the official Rome/Lugdunum/wherever coinage. I know many
provincials of the late Republic and
Augustus which have superbly realistic
portraits of
men and women of the period but I'm also aware that there are
provincial imitative copies of many of these issues in
poor style.
So, don't differentiate between Imperial and
Provincial coinage but do look out for
fine style portraits in either case. And don't omit the related family
members or the
rare provincial administrators if you can find them.
