My videos are always super long because i talk complete rubbish a lot of the time and i struggle to find things i can edit out where the video will still make sense haha! so i think my retention time is not very good at all for many of my videos tbh, so coming from someone who does that, I would only split up certain videos into parts, otherwise just do it in one long video if that would make sense. You could possibly do like 5 MORE things that annoy me about girls or whatever you are doing your video on with lists as that would make sense just don't call it part 1 or part 2, this is probably gonna make zero sense but i personally only split my videos into parts if im doing gameplay videos as they are always super long like nearly an hour.
I'm very tired and apologise if that makes zero sense hahaha
also turned out i said sense a lot of times! but what im trying to say is that you should just do one long video on a particular subject unless its gaming or something that could be expanded on on a later date