I tend to use the 02 insert for most of the work I do, usually small aluminium/brass/Plastic parts that don't need any larger fillet at change of diameters.
When cutting stainless or EN8/16/24 I change insert to a .4mm tip rad.
I only use .8mm rad when not cutting to a shoulder or facing to centre, the length of cut if using a roughing pass up to a shoulder is too great for the speeds and feeds I use on a small cnc lathe.
Emgee