I have various thoughts on this. If you're doing 3x3 @85% with a straight weight, and you only get one set of 3 at 90% after jumping up from 75% when you're doing the Westside style ME days, then possibly not enough volume to build strength. If you've spent a while at higher rep/higher volume stuff previously to that, then the Westside style will help you peak and be more efficient and display strength better, but not "build" it so much.
On the other hand, if on Max Effort Day you do something like 80% x 3, 85%x3, 90% x 3, then you have now got a total of 3x3 at an average intensity of 85%, but with a higher peak intensity. Same working volume as the straight weight idea, but more intensity.
Generally I count anything above 80% as "working sets", so if I did 80% x 3, 83%x3, 86%x3, 89%x3, and 92% x3 I have a total volume of 5x3 above 80%. That will almost surely be enough to build strength. Or if you did something like 80%, 85%, 90%, 85% as a "back off" set.
You can do the same calculation with sets of 5, or singles.
Obviously as the peak intensity gets higher you have to watch more closely for signs of nervous system fatigue, but in general yeah it works. The problem that I notice some people have with Westside style max effort days is that they are taking waaaay too large jumps to work up to their 3 or 1 rep max set.
The other thing that gets most people is that you have to remember if you're in a squat suit you might work up to 85 or 90% of your raw max before suiting up, then working up to a suited max. So essentially 1) you've come close to "maxing" twice and 2) all the sets with the suit represent an overload set compared to your raw squat.