The Truth About Max Strength Training Frequency
The Infamous Russian Sports Scientists Vladimir Zatsiorsky classified max strength training (the maximum effort method) as working above 90% of your 1 rep max (1RM) - I personally classify max strength as anything above 85%, but maybe I am not as hardcore as the Russian lifters!
It is well established that lifting maximal loads elicits the greatest strength increases. However, there is, of course, a risk of overtraining and injury when pushing things to the limit regularly.
I know many lifters that work above 85% multiple times a week, every week, and others that incorporate max effort lifts every 3rd week followed by a week-long deload.