CORGI essential for DIY gas work?

The Corgi guy who I use for my Landlord's Gas Safety Certificate uses a combustion analyser on the boiler flue. He also checks the flameout device on the cooker works. Presumably, if you check the working pressure at the appliances and compare it with that at the meter, this will show if the pipes are correctly sized. And a soundness test will go most of the way to check the quality of the joints.

A lot depends on whether he wants to do an OK, good, excellant or by the book job. If new work has been done it will almost certinaly be worth investigating thoroughly. Often I'm looking at the same kit I looked at last year. The first time I go to an installation I will usually find problems, susbsequent years I only have to check that things have not gone wrong. So the pipe sizing will be OK because it was last year. However the gas meter's working bits can and do fail also the main governor.

I find that a typical boiler + hob installation will take me 60-90 mins in total