Attenuation- how much might it vary?

I used WL 005 for my last two batches, sister slants from the same purchased liquid-yeast package, made into starters in the identical way. White Labs lists the attenuation range of 67 to 74%. The last two times I brewed I calculated my actual as 72% both times. One was mashed at about 153 degrees, the other at 150. I thought I should see a difference in attenuation between the two - the whole alpha versus beta thing. Hypothetically should I have? (I haven't had a chance to drink the second one yet to see if I can discern a difference in body).
Thanks for any comments!

Everything we as homebrewers read would lead one to believe that mashing lower will result in higher attenuation but you are seeing otherwise, and I typically see what you are seeing.

In my experience attenuation/final gravity is much more dependent upon the % of specialty grains in the mash than the mash temp.

I'm sure there is a noticeable difference between mashing at 148 and 158, but in general I never see much difference in the 150-154 window.

Agreed. I've noticed that pitching rate and health of yeast play a much bigger role in attenuation than a few deg F mash temp.