Game auto saves then you enter load doors, the image shows the new cell so you assume it saves after you enter?
It does not it saves the game before you enter the cell but uses the image from then you arrive.
This can be exploited for save scumming for legendary items, if you run into an legendary enemy just after you enter and he drop junk or items you don't need reload the auto save and try again.
Most of the time the legendary enemy is still there, he might however be changed from legendary supermutant to legendary supermutant butcher
He will have an new legendary item.yes you can even use an quick save after getting an item and try again and see if your luck is better.
Benefit of this that you don't have to do anything except reload as the autosave is there already.