Further investigation IR below 2 Megohms or 20 Megohms??

I was asked to investigate a low value of IR in a large, rambling GP complex. An EICR conducted by others had an unsatisfactory designation because the value recorded for a number of circuits was 0.16Mohms for which the contractor awarded a FI code. The surgery manager needed the report returned to satisfactory for statutory purposes. 
Three-phase installation with several 16-way TPN boards all with 3pole isolators with circuits neatly installed using single core cables in metal trunking/conduit. Hundreds of items of equipment connected. My view was that it was madness to conduct IR tests in the first place and expect a meaningful outcome. 
My rate for Saturday isn’t eye watering but it ain’t cheap either. I agreed same with manager and insisted that an electrician was on hand to assist. Real pain to disconnect the equipment and had to remove circuit neutrals but eventually tracked it down to these fellas. Several on individual circuits pulled the IR down. At 250v the individual reading was around 0.5Mohms. 
So if the guys doing the EICRs continue to do bonker things, I reckon there is a few quid to be made sorting the nonsense that is generated. I wonder how much these poorly conducted EICRs are costing clients across the U.K.! 

I was asked to investigate a low value of IR in a large, rambling GP complex. An EICR conducted by others had an unsatisfactory designation because the value recorded for a number of circuits was 0.16Mohms for which the contractor awarded a FI code. The surgery manager needed the report returned to satisfactory for statutory purposes. 
Three-phase installation with several 16-way TPN boards all with 3pole isolators with circuits neatly installed using single core cables in metal trunking/conduit. Hundreds of items of equipment connected. My view was that it was madness to conduct IR tests in the first place and expect a meaningful outcome. 
My rate for Saturday isn’t eye watering but it ain’t cheap either. I agreed same with manager and insisted that an electrician was on hand to assist. Real pain to disconnect the equipment and had to remove circuit neutrals but eventually tracked it down to these fellas. Several on individual circuits pulled the IR down. At 250v the individual reading was around 0.5Mohms. 
So if the guys doing the EICRs continue to do bonker things, I reckon there is a few quid to be made sorting the nonsense that is generated. I wonder how much these poorly conducted EICRs are costing clients across the U.K.! 

A three phase existing installation with several 16 way TPN boards - Id never expect a global IR test to pass......possibly with a LOT of lengths of run involved - even if you did each individual DB as a whole global IR test. Hundreds of items of connected (electronic) equipment.....DC rectifiers etc.....

Would it not be reasonable in this type of situation to use a milliamp earth leakage clamp meter on the supply to each DB to get a better determination of the possible state of the cabling IR? I ask because I do do this, and I'd like to check with others on here if this is generally accepted as reasonable? 

Shutting stuff down in a large GP complex must have been difficult/complex to determine the effects of. Not just of the electrical but the impact to the business too..