If you bill 160 hours per week and work maybe 200 hours, that’s still 1.5 to 2 percent of your time. I would call that non-trivial and worth at least looking into.
And my point is that a cost that’s 1 to 2 percent of your revenue every month is worth looking into and possibly reducing. Even if you decide to keep it for the time being, it’s worth revisiting every couple of years or so.