Put a Flat on Carbide Tools

Alright... I've been using carbide tools in set screw tool holders for years. I've made my own for smaller tools when I was using nonstandard
collet nose spindles for tools that were to small for the spindle. I've also made my own solid one piece tool holders with a setscrew.
I have to be honest. I've never really had an issue with using carbide round tools in set screw tool holders, but I am told that set screw tool holders "should only be used for tools with a flat." I do put the tool holder in a fixture and tighten the set screw with the maximum tool pressure I can put on a long arm hex key without stripping the screw (and sometimes stripping the screw LOL).
So, is it what I have been told true? Should I only use tools with a flat on them in set screw tool holders? If I do that then am I reduced to finding a way to put a flat on those tools? How would one go about that?
I'll probably ignore all that and just keep doing what I am doing, but I thought I'd ask.
P.S. I use almost exclusively carbide tools except for drills. I even have some carbide drills in sizes that see a lot of use. I have a few HSS mills, but I rarely use them.
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In my experience with mostly HSS, grinding a flat reduces mushrooming on the end of the screw because it doesn't need to be as tight, and the screw makes area instead of line contact.
If I can't easily surface-grind the flat or dog-point the screw on the lathe, hand grinding them is usually good enough.
If you can remove a mushroomed setscrew through the center hole it may not matter.
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    [ ... ]

    With the standard "Weldon flat", not only does the flat end of the setscrew contact the flat on the tool (typically end mill), but there is a 45 degree bevel on the end of the setscrew, and that contacts the bevels on either side of the flat, to adjust the extension of the end mill as the setscrew is tightened. Of course, this does not make the practical extension right on an end mill which has been resharpened, but it makes it consistent for that one end mill, and prevents either the end mill pushing back into the tool holder, or pulling down with the forces of the spiral cutting edge. So -- the extension will not change during the cutting process.
    With sold carbide end mills without Weldon flats, the extension may be different each time you put the end mill into the holder, and it may change during the use with cutting forces.
    My experience with the Weldon flats and the setscrews is with NTMB 30 or 40 tapers -- to fit either directly into my Nichols horizontal spindle milling machine (40 taper), or into the quick-change spindle on the Bridgeport BOSS-3 mill (30 taper). I also have the adaptor from 40-Taper to 30-taper to let me use the smaller end mill holders in the Nichols mill.
    Just some thoughts.
    Enjoy,         DoN.
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