What does everybody think about doing a service on time rather than km's?

I understand when oils were crappy that it may be a good idea, but with the oils we have now is it worth it?

My car is due for a 20,000km or 6 month service and I am at 14,000 is it worth servicing it already even though it only got done 10,000 ago?

Just want to guage peoples thoughts on this. I personally think its overrated but if I get convinced by what people think here, I will book it in.

Cheers