Tbf I think there needs to be a bit of come and go once kick off approaches. I'd bought decent tickets for Hibs but arrived just before kick off and elected to get soaked at the front for 90mins rather than be one of those guys and start causing arguments by moving folk.
At the same time if someone tries to move me at that time they'd also be onto plums. Bottom line if you want your seat get in in a timely manner.
Unallocated seating would be better anyway, this new breed of "ultra" likes to be stationed at the front, stand up and wave giant flags, blocking the view of folk behind them whereas the bams used to go to the back to stand up, not blocking anyone else.