I have a client who had koleston perfect me 8/0 with 6% full head tint pre lockdown. She wants to go a bit lighter, I have decided on 10/0 and 10/16 with 9% to avoid too much warmth. I want to do mid lengths and ends first, to avoid hot hoots. Would you still used 9% on the roots or mix with some 6%? She has a fair amount of grey, but need the 9% to lift.