As far as my experience can tell, this effect cannot be seen in OFDM systems in a way that you can certainly attribute it to the word length. So I’m guessing (out of my own experience, without being sure) unless you increase WL by a very great amount, the effect is not that much.
I think for every system one can increase the WL and see if they can observe any PATTERNED changes. So I suggest that you do this if the accuracy of results from a system are very important. Nevertheless, simulations that can be repeated for systems of the same type by anyone and yet give more or less the same result would be scientific and reliable.