trojan,
Your understanding is correct - if you are 5 yrs on a policy, all pre-existing conditions are fully covered, according to the cover on your policy.
No waiting applies and no need to worry.
The angle I think you are missing is, if you change to a policy with better hospital cover - for example with extra cover for a private room
in a private hospital. There is a 2 year waiting time applied only to pre-existing illnesses and only in respect of the extra cover on the new policy.
The pre-existing illnesses would still be covered in full according to the previous policy. All new illnesses arising are fully covered on the new
policy from day one.
Regards, Snowyb