In my last few years before retiring I was moved to what could be called a general services department, though I don’t think it had such a name.
I was given PAT training and part of my general services was carrying out that.
I learnt that an organisation (this could be a company or a voluntary society) can test its own equipment provided it is happy to show the testers are sufficiently competent, and work to the proper process itself and to the desired frequency. For power-tools heavily-used in rough conditions that might need be six-monthly, for office equipment, two or three years may be adequate; but the management has to decide that in a sensible way.
Most of our equipment was tested annually; some two-yearly I think. Anything special, such as a prototype; before first use.
Computers are a special case because they are too easily dmaged by the ordinary PA test applicable to a power-drill or a kettle. One reason the company moved its PA testing to internal staff was said to be a contractor damaging a lot of IT equipment by not testing it correctly.
In a way, it was rather like our club scheme for testing boilers: ensure the testers know what they are doing, and follow the instructions! The horror stories of managers destroying perfectly good equipment and the like, suggest to me incompetent senior management loading people with responsibilities for which they have not been trained, have no experience and are given no support.
Sadly, I fear such middle-managers act as they do out of both fear of the responsibility, and fear of admitting ignorance, so need learn what they and their staff are supposed to do – and what they are not supposed or do not need do.