Minimum words for a TOEFL® essay

[Enyan]

Hello,

first of all I wish to thank all of you for this very usefull website.

I am preparing for the TOEFL essay and I see that I the time reaches very often the 30 minutes time before I write the 300 words. But this is because I try to correct mistakes, check or change essay composition.

is the score for the essay affected also by the number of words being used?
For example I often end up with an essay of about 270 words.

What do you think?
thank you very much

TOEFL listening lectures: A university lecture in Biology