Oil is the life blood of your engine...
Vic.
Absolutely agree with that and more.
It's the largely arbitrary nature of oil change intervals which I question. Then it's the rip-off charges of too many garages (in the UK, anyway) which for them, changing oil and filter, is just a 10 minute job.
Having said that, I always stick to the manufacturer's service schedule and/or with my GE Jazz I follow the on-board service display recommendation for oil (with filter) change.
To do otherwise can be the most false of economies, that's for sure. Particularly if keeping the car till high miles. And in that case, changing oil sooner rather than later can be a wise policy.
Oil analysis ensures oil is changed when it NEEDS doing... not before and not after... which is the problem with arbitrary oil change intervals. (Which, I think, is jazzman's point.)