First, it is never too late...but the earlier you send out apps the better. Check the deadlines for the schools...when that date has passed, it is then too late.
Second, I think you are asking the question to the wrong group of ppl. I would read the directions carefully...most schools sepcify how long they wanth the secondary responses or only leave limited space. If that does not give you the answer you are looking for, I would call or email the schools. In general, I would attempt to be as brief and concise as possible while fully answering the questions. Nobody who looks at hundreds of these applications is going to read 500 words of fluff that could have been written in 100.