Dtyke:
"I have no issue with componants and equipment which are extended due to testing etc. My issue is 'footfall' in and out of the seat which has the potential for damage to the componants on the seat which increases over extended periods. For example the amount of dirt from the underside of boots/shoes that collects in the seatpan can be considerable even after just six months. Also the longer the seat is in the longer it is subject to weather, the canopy does not always get closed before the rain arrives!"
I'm not picking on you Dtyke, just answering the post.
If your inspection periodicity covers this exposure to damage and you're still not finding faults then there is no real issue in considering extending the period.
Safety Critical Component inspections can be extended by the right TC holder. e.g. Boeing deleted all the periodic inspections of some 737 APUs from their AMP (including oil changes) as the inspections didn't prevent anything happening.