well I was always taught that it was a no no, and although there is no regulation against, I consider it bad practice, connector blocks should not be used in switches. Even if you were to use double pole switches, it would not help with 2 way and intermediate's.
In my 25 years of sparking, I can honestly say that I have never seen it.
I think the difference is having a decent apprenticeship where you was taught what was what, and not what these new kids on the block get taught at college today, then go out into the big world of sparking without any practical experience.
Reminds me of something I saw about 6 years ago working on the CTRL for Drakes (Emcor). basically it was a conduit system that had been 3 plated in singles, and the switch line and feed had been taped together as if it was a twin and earth to go down to the switch, ( brown and blue had been used, and the blue had brown tape on it), and was just so much easier to 2 plate it.
Made me laugh no end, as the guy who did it was always saying 'I am the mutts nuts'
alright Colin you still out there mate?