As with many photographic rules, those relating to light and lighting are fairly disposable. In fact any particular rule should really be prefixed with something like "If you have no clue and haven't done anything like this before then start here…".
I've blathered on here and there about the Profoto 4ft Octa quite a bit as of late. One of the things that makes it great is within a fairly wide range of distances it's pretty much set it up anywhere and get decent results without paying a ton of attention. Of course paying a lot of attention will always yield better results it does allow concentration on lots of other things and a high degree of subject flexibility.
Going to the other side of the equation is "hard light". In all honesty I would say hard light is probably my favorite which everyone knows shouldn't ever be considered when working with people, especially if you want "pretty people" right? Wrong. Well, sorta wrong. I'll explain.
Like many rules, they can be an easy button to reduce the opportunity to go really really wrong. On the other hand they are bullshit. Hard light can really show and emphasize crap tons of detail you may not want to see, such as skin texture. Of course that completely depends on where you cast shadows. Above is an un-retouched frame using a Profoto Magnum reflector and grid. It's also at fairly extreme angle in terms of casting shadows. The Magnum is a large reflector as hard reflectors go. Used close up it's far from a point source and much larger than the face of a speedlight. Theres another kicker light coming from behind and camera left that's even harder. A bare Profoto D2 with a 20 degree grid.
If there is a problem here it's complete due to that kicker. That problem isn't due to it skimming Jenhanne's black hair, wardrobe, or even that slight edge of her jaw. It's entirely due to picking out the light colored hairs and making them go nuclear against a shadow area of her face. While I personally don't consider it a problem, that's what hard light can do. In fact that's what I like about it. Probably should have tweaked the angle of it just a pinch, of course it was tweaked but any subject movement will change the way it shows. Even an inch. Hence rules are just really short-cuts and easy buttons.
Here's a random frame that shows a tiny change in angle of J.'s head upward. I have no idea how to even estimate the change in angle. One degree? Three? Five. Note the complete change in shadows and even with that kicker from camera left still highlighting a few light colored hairs they aren't against a very dark shadow any more. Of course you could lower the light a bit instead of Having J.'s face tilted up a hair more.
Another random frame angled upward just a hair more. You see where this is going right? Unlike a giant source that makes not a ton of difference with small changes, hard light has tons of variations with tiny changes.
Generally speaking the "softer" the light the more generically "beautiful" it can be but kind of bland. The harder the light the easier it is to produce something truly horrific but some of the most "beautiful" light I've see happens to be from relatively hard sources that dance and play on the scene.
These frames from a quick session don't even begin to consider fill ratios as all of them are with zero fill from any reflectors or fill sources which changes the equation even more. The image above is one of the last images I shot in the quickies I made. There was one tweak to the lights. Actually the tweak was for a third light I didn't mention yet. The background light that's producing the gradation from brighter in the lower part of the frame to darker higher in the frame. That's a Profoto B2 with a 20 degree grid. In that last frame I upped the power a bit and angled it a tad higher which is why the top of the frame is lighter. The vignette seen is in camera not post. Everything else is the same.
Photos made with a Canon 5DsR and 24-105 f/4 L. Various random color treatments with slight differences processed in Capture One Pro 11. One main light, a Profoto D2 with magnum reflector and 10 degree grid, a bare-face D2 from behind and camera left, and a B2 with 20 degree grid pointed at background and feathered to produce the background gradient.
That slim vertical rectangular shape on the background seen in a few frames is the sun peaking through a window behind the white seamless background paper. I eventually got rid of that for the final shots.