Well, I've toyed with the idea of attempting some simple (I thought!) animation...and now I've given it a try!
It's now 15 hours 50 minutes into that render of a 40 second duration (961 frames) video and its just finished frame 488! I kept the image small & simple, I thought, with a camera simply revolving 360 degrees around two static central characters.
I'm sure there are settings that can be used to improve that render speed but this is new territory for me. I'm determined to let this one complete but some more research and a faster computer will be necessary before I venture back into this area again!