You and I aren't saying the same thing. The occasional 30 hour week is the consulting fact of life called "utilization rate". Consulting firms don't get to balance out utilization with overtime. You don't make up the 30 hour weeks with 50 hour weeks.
The firms I know that have a culture of semi-frequent 50-60 hour weeks pay OT rates for the off-hours work, regardless of prior utilization rates for those consultants. This is a manifestation of the classic consulting problem of "sales vs. delivery". It is not the consultant's problem if sales stuffs the calendar full of too much work to staff in a 40 hour week.
The firms I know that have a culture of semi-frequent 50-60 hour weeks pay OT rates for the off-hours work, regardless of prior utilization rates for those consultants. This is a manifestation of the classic consulting problem of "sales vs. delivery". It is not the consultant's problem if sales stuffs the calendar full of too much work to staff in a 40 hour week.