Yeah it can be hit and miss depending on how the individual stores handle it. When I lived in Manchester, the queue used to start at around midnight, but the list of what they had in stock was released online before hand, they would also walk up and down the queue handing out print versions and more importantly announcing when things had sold out, so if you were there just for that one popular record, you wouldn't need to continue queueing to find - they held all stock behind the counter so you went and asked for whatever it was you wanted.
The place I live near now doesn't do that and even worse, only allows approx 4-6 people in the store at any one time, to browse them (stacked in literally no order), so if a group decides to spend half an hour 'browsing' with only one of them buying 1 record, tough poop - thats half an hour everyone else is stood outside freezing until they pay/leave (because it's always cold on RSD)