I (and well... lots of people outside of the para-RP-crowd) would find 'between multiple paragraphs and short 5-8 lines' with 6 to 10 minutes wait to be ... quite long. Pretty much all (except, apparently, para-ers themselves) would call that para RP.
I am not saying it is 'wrong'. Preference, ultimately. I am just noticing the huge gap between what are called 'one liners' and what you are describing. I mean... there is quite some distance between 1 line and...5 to 8 being 'short'.
I guess the many RP-ers that fall in between (probably not considered 'true RPers' by some) are left to seek each other out in sims dominated by one-line RP-ers. Because, as soon as a sim turns into a 'serious RP sim' and gains traction, it usually flips para quickly.
One sim owner I know even goes so far as to kick para RPers out of her 'mixed' sim, as soon as they start showing signs of insisting others adhere to para RP conventions. She argues that they will soon set the tone, dominate, turn others away. And then pick up their ball and go play somewhere else, leaving the sim empty.
Not my problem, fortunately, but if I were to do an RP sim and try to steer towards my own preference, I'd be hard pressed on how to deal with the problem of, on the one hand, making a sim focused on RP, but at the same time, trying to stop it from becoming the playground of aspiring novelists. Maybe I'd hand out emoters with an in build 'twitter'-like function. Go over a certain number of characters, and it turns red, telling the players that their post is running too long.
(Good thing for me that this forum doesn't have that function, btw.)
Actually... I wonder if an RP sim like that might not become very popular.