Normally I'd agree but since most vehicle owners don't do PM's, especially brake fluid service intervals. Example: About 6 months ago a customer of mine brought me his 2003 P2 XC70 and the brake fluid system was totally contaminated.
The Master had to be replaced because seals were failing and if I remember correctly one of his rear brake calipers was leaking at the piston seal. I had recommended replacing the MC, rear caliper, the soft lines to caliper, doing a total flush of entire brake system. It looked like someone had introduced a foreign substance into his reservoir.