In 99% of the cases I always miss all the deleted scenes in movies. Same goes for Alien. I just recently rewatched the deleted scenes and it was only the second time ever I saw them, and the scenes of them talking right before going after the chestburster and then after Dallas gets killed are just so immersive, powerful and incredibly real. I actually forgot I was watching a movie and got really spooked watching them. Thats the power of Alien and how it can create a certain feel and evoke fear