Yes. Five. As opposed to 'max four'? I suspect you and I will forever disagree on the term 'packed'. I'd count ' The Underdark' as a packed interior. Mind you that in the Svirneblin Inn part alone, there are just about 15 containers, some of which locked, that hold..... Thirteen gold pieces. I don't have any savegames ready, and I'm not particularly in the mood to send Ms Screenshot on another holy mission... I certainly hope you get the idea. If not, then, sure. By all means, consider yourself trolled. I advise acid or fire.
They certainly reduced the number of containers in BG2. Many areas indeed only had 4-10, yet filled multiple screens. Especially in dungeons most containers had relevant loot, so weapons, armour or money/gems/jewelry. There wasn't much "trash loot" at all. Even trash loot was often never sold. I recall that I looted a broken sword from the Duergar in Irenicus' forge and I kept it until the end, although it was totally worthless. I thought I could make a sword out of it.
If we go to an inn or so, indeed almost every room has a chest, or a cupboard, but that is five or so on one screen. I went downstairs into a cellar of a hourse in the blighted village and there were 4 chests that were marked when pressing alt, around 4 vases/urns both lootable and only interactable, 10-15 barrels and 10 crates, lootable and interactable. All of these were unmarked. Along with a cupboard, couple of boards on the wall several items on the floor, probably a couple of candles, chandeliers, books, baskets and so forth. That is around 40 or so interactable objects in a room with no gameplay value, there are no mobs, there is no riddle or hidden lever behind crates. If I recall correctly however there is a quest-relevant item in crate no 7. Of the containers likely 5 or so are filled, so if you are on a bad streak you might miss that object because looking at all takes several minutes. That is just a bore and a chore.
