So for me there's 4 ways to tell a historical story:
Dramatic Documentary - Follow the historians to the letter come what may. You're going to do it correctly.
Dramatic Interpretation - Follow the historians for the most part, combine a few minor characters, tinker with some minor chronology. You're only adjusting it to make it fit the medium better.
Epic Interpretation - Read a few books on the subject, write the script like its your novel, jazz it up with Hollywood tropes, make it over the top. Accuracy be damned, the story needs to be told.
Epic Failure - Skim some Spark Notes, write a script without knowing how, hire some low budget actors, tell the historical experts off, you know what you're doing. You don't know what you're doing, its going to suck.
Vikings is a good Dramatic Interpretation. Spartacus was in the space between Dramatic Interpretation and Epic Interpretation because it was actually fairly historical in terms of events and characters, just really over the top. Braveheart is pure Epic Interpretation. Ironclad if you've seen Lindybeige's multi part review is an Epic Failure.
Most good attempts are going to be Dramatic Interpretations or Epic Interpretations. I think writers and directors are afraid of following too closely because they don't feel in control of their vision. Not to mention your minor mistakes like the wrong number of buttons or something will still come back to haunt you...
Every director and screenwriter sees themselves as an artist and for them they have a creative license even when dealing with historical events. Just like Homer used some creative license when describing Odysseus's voyage of return.