I find using a 3 flute carbide roughing cutter then full depth 0.35mm finish pass with twin flute is best setup with aluminium using 2.2Kw spindle.

I can easily cut 5-6mm DOC slots with 8mm serrated edge roughing cutter between 900-1200mm/min 15000-20000rpm. This setup gives me good material removal rates along with excellent finish and best tool life.
Using above rougher I can cut 10mm DOC when pocketing with 45-50% step over.

In all cases using air/mist.