I have voiced a concern over ejection seats on this forum before. I did three tours in Seat Bays servicing them and three tours on Sqn's fitting them.
Up till the early 80's seats went to the seat bay every 6 months, the 6 monthly was mainly a visual with a complete strip-down every 12.
This then changed to every 12 months, it was not unusual to go out to the Sqn's between this period to carry out minor repairs to mainly fabric parts and very rarely damage caused by the many people getting in and out of the seat (there are levers and linkages along either side of the seat that could be damaged if stood on).
It was then changed to every two years (more bay call outs)
As I left 4 yrs ago I cannot confirm 1st hand but believe this is now every five years and some seats are crated up and serviced centrally with no bay expertise on units.
I remember a senior officer telling me it was 'acceptable risk management' and not a money saving exercise........................ !