The more modern approached to this is found here:
VST plug-in locations on Windows – Steinberg Support
And your old school default position you listed under “Personal Notes” is not really relevant as any path containing (x86) is for 32bit VST2 plugins only - which are extinct now.
A better approach is this listing:
Any and all remaining VST2 plugins from any vendor are 64 bit and my default is the first folder location listed:
C:\Program Files\VSTPlugins.
Works like a charm and pretty much all vendors who still ship 64Bit VST2 honor this location by default.
S