Only really ever seen that in listed houses or houses with old flint type walls where chasing is impossible but yes obviously only ever run singles in conduit
Amongst my many electrical qualifications I have which includes the 17th edition to the new amendments, the green book, it never states skilled persons holding certain qualifications.
Obviously you'd never get a job in the industry but it specifies a competant person. Now what quantifies a...
Of coarse you can.
The regs only ever mention a "competent" person
With that in mind, you could effectively do any electrics at home but always get a sparky to test it.
I'm fully qualified by the way.