If you want to TEST to find out if a circuit is safe then you HAVE to go through the tests one by one.
If you just want figures to put on a form to get paid then there are all sorts of ways to cut corners but YOUR name on the form and as a professional it could be a criminal charge if anyone gets heurt or worse.
Zs is a live test to CONFIRM the previous DEAD tests, it should be done on the point tested with the highest R1+R2 figure, it assumes you've actually tested at each connection like it says in the book and if you tabulated those readings then you get a good picture (electrically) of the circuit, bridges in rings etc.
Never have understood why there are no official forms to record your circuit testing results instead of just one on the summary as that just leads to fudging to get done quick as it doesn't ask where exactly on the circuit that reading was taken as it's a summary, not specific. A Ze then a Zs on each circuit, turn off main switch, short the neutral & live bus bars to get an insulation resistance of over 1M ohm and out the door to get breakfast.
Rings are relatively easy to test, radials like light circuits get hard as EVERY switch has to come off to get to the CPC to check continuity unless it's an intermediate but you often can't tell that until the plate is off anyway.
Depends on what type of person you are, not give a stuff if someone gets hurt because you cut corners or someone who takes a pride in their work. Sadly I'd not want to put my name to much work I've had to test and yes I do test my own thoroughly so I pick up my own mistakes.
Get a copy of GN3 Inspection and Testing from the IET. Explains it all better than any third party books.
