hahahahaha ............... the original belts in the early Mks were made of, effectively, kevlar ....... and this is just about indestructible, they make bomb proof bins etc from it !
I have tried to get from Lexus the make-up of more recent cambelt materials but haven't been able to elucidate a sensible reply.
If your last cambelt was OEM then you're probably ok for a while yet.
Regarding servicing and all things Lexus, my local indy guy has been looking after my cars very effectively and economically for approaching 8 years ( Mk1, Mk2 and now my Mk3 cars ) and he does what he does very well indeed.
What did let me down quite catastrophically was the front cooler pipes for the pas fluid, these rot out about now but mine also rotted out the steel complex pipework up into the pas pump area too ....... Lexus bits would have been prohibitevily expensive, repair effected by copper tubing ( no pressure ) and flexi hoses and clips .......... . but get it done, it's a cheap fix and will save a huge amount of grief. This is an achillies heel of the Mk3
Malc