For most part and this is just my own opinion is that and IR test should be done for initial verification ( commissioning the install )
Do we really need to IR test an install as part of any further EICRs ? Only I guess if something looks dodgy or you have some sort of intermittent fault for example.
I honestly don't feel IR tests are needed as part of any sort of basic periodic inspection
I,m slightly off topic here ,but I felt I should say that I,m largely in agreement with what you say.Certainly ,I cant see the point of extensive electrical testing of a 5 year old family home ,when in reality a thorough visual inspection should suffice (plus testing of all safety devices).
Now a 50 year old home ?Thats a very different matter.
But whether 5 or 50 ,I regard extensive visual checks as my number one source of information in determining the health of an electrical installation.Standard electrical testing then supplements it.
Did a periodic on Wednesday on a recently renovated older house which is up for sale.Looked great and I felt optimist.All the standard testing gave excellent results.
When I began removing accessories though I discovered undersized wiring at many sockets.Secondly the new wiring visible at the DB often extended only to the first point on the circuit where it was joined to the original wiring.It all looked professionally done too.It set off alarm bells immediately.
I dont believe it possible to experience "a breakdown of insulation" in a modern home,certainly not through deterioration.And as Dusty alludes to the insulation is only really compromised (in my experience to) when some unconventional activity has occured in the home ,be it intentional or unintentional and this will almost always manifest itself either visually ,audibly ,via odour or through operation of one of the safety devices.