Dana M. Hague wrote:

For the most part, when flying VFR, it doesn't matter all that much.
However, constantly climbing and descending is inefficient, uses more
fuel, and it's just plain unprofessional.

It is also unsafe. The cruise altitude rules can get separation down
to 500'. In addition, altimeters (even if set correctly) might be
off by 75 feet, ... there are a lot of things that add up.