The whole point of a circling approach is to remain visual with the airfield and NOT to follow any magenta lines. Once the approach path has broken off from the ILS (or other electronic guidance) The pilots MUST remain visual.
Absolutely correct.
Problem is, IMHO, that many airlines (mine included) train for such procedures in simulators where you lose sight of the runway going downwind and only pick it up again when you're halfway round the turn onto finals. The display of ground/terrain is rather half-hearted as well. The end result is that you fly it partly on the map/DME, etc. because there's little else to refer to, so it becomes a hybrid instrument/visual manoeuvre rather than a purely visual one. Not good procedure.
If you do plenty of this kind of approach in real life, no problem, but if you were not current and forced into circling at short notice in bad weather, you might try and make it easier by using the FMC/map "as a backup for SA", maybe even drawing a little circuit on the screen. Easy to press '7' when you meant '4' as they're next to each other...