The -535 uses "on-condition" maintenance principals so you only have to remove it for a life limited part going timex or else if you have a problem (e.g. turbine damage outside limits). However....most operators will have an expected life based on rating, average de-rate, stage length, route network etc.. This is true of all gas turbines though.
On the fan blade issue, the original RB211-22 had wide chord composite fan blades made from a carbon composite called Hyfil. While it survived most tests during development engine running in '69/'70, it wasn't up to a bird strike and this resulted in the switch to a Ti clappered blade. This late design change along with a number of other factors (general RB211 performance, exchange rates etc.) pushed R-R into bankruptcy in 1971. The wide chord blade was next introduced onto the E4, this time it was a Ti blade.