I am caught in between giving this a 4 or a 5 so 4.5 it is.
Once in a Lifetime does a lot of things well but it also felt a bit lacking in some aspects. Contrary to what I usually see on the forums, I actually prefer HS graphics so the art and animation is a plus for me. The jokes are also pretty funny and I like how some of them are conveyed simply by the camerawork.
Looking at the heroines: Judie and Lauren are pretty good; Iris, Aiko, and Jasmine are okay; Carla and Rebecca could have been better. Iris is an odd one since she's not really connected to the main story but she was immediately accepting of all the weird stuff going on with the main trio. The treatment that Carla and Rebecca got sucks for me since older women types are my favorite heroines. Their character stories felt disjoint from the rest and that highlights one of the aspects of this VN that felt lacking. There is not much interaction among the girls aside from them interacting together with the MC. We have Judie-Lauren, Judie-Iris, Lauren-Aiko, then Jasmine, Carla, and Rebecca by their lonesomes. The harem ending is nice and all but the transition to that state was abrupt like, "Okay we're all going to move far away, this is everyone coming with, and by the way I'm having sex with all of you," Carla and Rebecca just accept it as if Carla doesn't mind that you're fucking both of your sisters and your cousin (though to be fair you're already fucking your mom) and Rebecca doesn't mind that you're fucking with your family members. I really think that part could've been smoothened out.
Special mention to Stabby Mike. He was an amusing fellow and it was nice to see him pop up once in a while throughout the story.
Overall this VN was a great experience but it fell a bit short from being perfect.