Close to 25% of the films on my top-100 are ones I've only seen once. Thing is, many of them are things I watched more recently but aren't new films. This is the difficulty. Whether it is The Apartment or Spring Summer Fall..., I think it is important to give it time before revisiting it, but I also don't want to leave it off just because I've only seen it once. Some of the stuff I've seen a bit further back have other things. Metropolis, for example, I will be rewatching once I can see the new recovered version.