I notice it is quite difficult without consistently buying ironite to keep your head above water at 1700 VP but I have not put in the effort that others have to know for sure what would use up more ironite.
I defintely don't spend ironite consistently (0-2 SoW refills per week I'd say) and I have had no troubles staying above 1700 VP. Perhaps I've just been lucky with getting less attacks than others?