If you have not had an ABS system issue getting a brake fluid moisture tester might be worth while. Got a decent one on Amazon for 15 bucks, it is THE issue with brake fluid and will tell you if it is time to purge. The guidleine of 100K is appropriate, but knowing the condition is better.
I check it periodically on my all 4 cars. Won't wait for the 100k or 3 year guideline. What i know is, DOT 3 high temperature version lasts longer than DOT 4 which attracts moisture much faster.
You might be right about 100k (presumably miles), it's not that far out of line. Still, if I google I see much shorter intervals. Toyota USA says nothing. Toyota Canada used to say nothing, but some time around model year 2014 started saying 3 years or 48k kms (~30k miles).
