I have to take regular doses of painkillers, and have to take the pills out of the blister packs in specific order. Paracetamol tend to be arranged in two rows of four either side of a raised ridge in the middle of the blister pack. I have to remove them in pairs either side of the ridge. Same with Ibuprofen in 200mg doses. Codeine comes in various different blisters, but I only take one of them at a time, so I only feel right taking the middle row in a three row blister first and then starting on either side. I'm only ever really happy when the two side rows are matched up.
Mrs Cube tends to take them out randomly if she ever needs them, and the other day she earned a bit of advice as she'd taken two out from completely random parts of the blister. She thinks I've got my knob in the Jacobs.