Yes, these are useful techniques.
Bouncing off of a white wall or ceiling, or off of the join between the two so that some light is coming from behind and some from above is great for a lot of informal photos where colour accuracy either doesn't matter or can be easily corrected because only one light is used - and an added reflector counts as a single light because the light that it reflects is, in that situation, from a single light source and so is the same colour.
But it doesn't work if we use more than one light. Even if the reflective surface started life as pure white - and there are lots of different white paints - they do tend to yellow with age, so a colour mix that we may not even notice with an informal portrait simply won't work at all with anything that's colour critical, for example products that need to have accurate colour, fashion, all sorts of things, once another light source with a different colour has been added..
This was noticeable with this tutorial shoot, but the subject was muffins, nobody knows what colour they should be so it didn't matter if their tops were a bit warmer than they actually are.
And then we get the potential problem of the angle of reflectance, again not really a problem with informal portraits, but if we're using a ceiling instead of a softbox to light a shiny subject that absolutely requires the light source to be at a specific angle in order to create the required diffused specular highlights, we just don't have the control of angle that we need, so are pretty much limited to either a softbox or to bouncing light off of a white board that's been set at the required angle - and getting that angle right with a softbox is much easier
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Firing a flash through a diffuser panel is also useful, but it may be easier to use a shoot-through umbrella instead, and which may diffuse the light more evenly. But, the problem with both is that about 60% of the light passes through, the other 40% bounces back and creates uncontrolled light pollution.
With this shoot, I wasn't trying to emulate a softbox, I was trying to create a natural-looking light from above and behind that was not only much too far away (about 4') to be soft, but was also far too small, especially at that distance, basically just a small irregular pool of light, covering a small distance - very similar in effect to creating a graduated specular highlight, the sort of thing we might use to light a camera lens, and here I'm thinking of the black on black lighting challenge. , ,
And, I used the same technique on this shoot too, for the same reason, the lighting from a softbox would have been too "gentle"
https://www.talkphotography.co.uk/tutorials/creating-very-hard-lighting-to-emphasise-detail.172/
