As somebody with a similar job profile & experience I totally agree with you, but do think the point of keeping mathematical relations between sets of measurements is a very good tip indeed:

not because not doing so would result in bad design decisions, but because it makes it much much easier for people unfamiliar with design work to:

- keep things consistent - stay within a balanced set of measurements that are easy to remember and expand - avoid ending up with a set of values that are too close to each other to meaningfully impact the design, but are therefore hard to maintain and identify