You definitely need to come up with a test schedule that works for you. I have one day a week when I regularly need to look reasonable, as I'm representing the RNLI facing the public and didn't want to embarrass anybody, so I timed my trial to give me a full week before I was due in the shop. That was enough to establish that it was bearable in public. I'm not sure if your "rinsing" is as vigorous as it can be - you want to "wash" your hair just as you would, massaging scalp etc, just without the shampoo. You can use a little conditioner if that helps. Ah g'wan, you know you want to have another go.