If you have some of those legacy lights (where they're like 12 or 15) there will be too many lights all over the place for any one of them to actually cast an effective shadow, depending on how they're positioned. I tend to use IDL now in all my images and 1 light for all outdoors scenes. And a sky-dome.

Indoor, I will have multiple lights, but one will be stronger than the rest if I want distinct shadows. I'm just in process of setting up an ICU scene where lighting is more diffuse.

Mind you: IDL is not perfect. I've an image that - I think - illustrates that schmutz Bagginsbill was referring to in that VRay thread by MistyLaraPrincess:

Where her body meets the couch the shadows are really meh.

IDL quality was perhaps a bit low: 7. Pixel samples: 9. Post filter size: 2 (sinc). and raytraced shadow samples for the only light (inf, map-size 1024, white, 220%, RT SBR: 6, SMB: .3) was 60. Still too low? Oh, no AO. Dunno if this was a good idea or no, but I did add the skydome as a light-source (diffuse_value:0, ambient_value: 1).

Well, back to the main shadows: they seem okay. Just not the ones at the skin/couch intersection.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks