I use ChatGPT to watch 2hour long YouTube videos and then ask questions to them. to my surprise, it does well.
the same thing happens with PDF, instead of reading a 300-page white paper I feed it into ChatGPt and ask it to summarise.
I learnt it from this ebook - https://hubs.ly/Q020FqjF0, it was a free one and pretty useful too
I use ChatGPT to brainstorm ideas by setting a timer for 10 minutes and letting it generate different concepts, then I filter the best ones for my project.