Its all about preference, we all have out own and we tend to attract what we are. Fortunately for Iwaku, a lot of RPers and GMs are not like this. Most Gm's don't even touch that whole "I require this amount of words per post" thing. It never really hurts to ask for more than 3 sentences though.
I do feel that more than 3 sentences is needed for me to have something to go off of...I do not like RPing by myself, and if someone doesn't put in the equal amount of effort or more, than I mid-as-well write by myself because that's what it feels like "To Me". Usually if someone requests an absurd requirement of posting I ignore it and move on to something else.
Having high standards and requirements does not always mean someone is an elitist either, while it can make us feel belittled or intimidated, sometimes being challenged makes us better and proves to be good practice