Well anything on a phone is going to be long, including summaries. I've read a short chapter of like 700 words and it seemed liked a never ending saga....lol.
I've seen a few that have had 16 sentences. It didn't bother me and it didn't give away the whole story either.
I really just think it's a matter of personal taste. We all have pet peeves when it comes to the site, fan fiction and life in general. I'm sure we could go on for hours talking about them....lol.
I don't think people should abuse the sumarry rule and post a whole chapter, but I'm okay with a longer summary if it doesn't go overboard in telling the whole story or repeat itself.
Sometimes I think people don't actually read the summaries anyway. I think they look for who the story is about and if it's about the guy they like they read it. I don't think I've ever gotten a review that said, well I really am not into Nick, but your sumarry was so captivating that I just had to read it. Personally, I'd love that to happen, but maybe it's a wish of mine. I think people are definitely more incline to read stories about the guy/guys they like more than anything.