I avg about 8k miles a year and my dealer told me I have to service my truck based on "whichever " comes first. Since I don't put too many miles, I have to service based on "time". Look at your maintenence schedule booklet.
Of course less is better, but only matter of cost on your wallet for minimal gain. Do you do 10k miles per year? What does your owners manual state, I don't own a 5th gen. I believe 5th gens are 1 year/10k right? (double check me though) if that is the case then just follow the manual Toyota built your engine they know what they are talking about.