Sure, but then if they don't take the blood at the specific prescribed interval and there ends up being a problem, they then get sued to hell for not perfectly

Sure, but then if they don't take the blood at the specific prescribed interval and there ends up being a problem, they then get sued to hell for not perfectly following the established ideal medical procedure. "Why didn't you catch the issue earlier? If only you had done the tests on the prescribed interval rather than delaying."