I use the CNMG 80 degree diamonds for almost everything. The 35 degree diamonds are useful if you are profiling really tight corners. Only time I use a left hand bit is for turning to the right up against a shoulder. I generally keep my bits perpendicular to the workpiece. The tooling manufacturer has spent a lot of money coming up with optimum shapes for their tool bits, and I am not going to improve their cutting ability by randomly angling it 15 or 20 degrees off of perpendicular. Think about a cnc machine... the tooling is always perpendicular 9or inline) with the workpiece.... no other choices. The only exception to this rule is maybe a unique cutting geometry results in having to come in at an angle to get the shape I need (like putting a bevel on a workpiece where the compound doesn't feed right to get it done). HSS btw (High Speed Steel), not HHS. For carbide, make sure you are using the right grade/finish. Get some really sharp CCMT/CCGT inserts for cutting aluminum, save the CNMG TiN inserts for steel.