For most parties we attend, we usually allow around an hour and a half to get unloaded and set up. In 99.9% of events we attend, this is more than enough time to get set up. A factor which can drastically increase the amount of time it takes to unload is the distance between where we can park, to the setup area, as it usually takes several trips back and forth to get all the equipment to the setup area.
The vast majority of venues we end up playing in are on the ground floor, and the distance between where we park and the setup area is reasonably short. Unloading is done fairly quickly, and we can crack on and get everything set up.
Occasionally we come to a venue where the function room is on a first floor, which takes a little longer as we will need to get gear up the stairs…but usually can be done in a reasonable amount of time.
Then we come to venues which are a certified nightmare. One of the worst was a hotel near Stratford upon Avon, which had a function room on the very top (4th) floor and even with two of us, it still took over an hour to unload (let alone set up), and the same again when it came to packing up. We parked as close as we could, but the route still involved: going down some concrete stairs, across a small courtyard, through a double fire escape door, along a corridor to the lift, up the lift to the 3rd floor (as high as it went), along a narrow corridor, up a flight of stairs and into the function room, of which the set up area was the far end from the door.
So you see that venue layout is important to any company that has to bring equipment into your choosen function room, and quite simply the further distance between their vehicle and the function room, the longer it takes.