Yep. Fixed heads can't be beat. I shoot slow trad bows and use nothing but fixed two blades and I get a pass through on most every deer,unless I hit a shoulder blade on the back side. Penetration would go something like this. Of course, with well tuned bows.

Best penetration;
Fixed double blades with small cut diameters with a progression to less penetrationby number of blades relative to cut diameters with larger having less penetration. , ex. Two better than three, three better than four, etc.
Then mechanicals.

With that said:Todays fast compounds, you can fudge around to get what you want. Bigger cut diameters for bigger holes, more blades for more blood, etc. But with a well tuned compound, you should not be having issues with penetration. You might want to up you foc or go with a heavier shaft.