Time Trial / Time Trialling / TT

No and no.

I'm entirely convinced that a power meter is a very useful (maybe the only useful) tool for measuring the effect of a training block. It's also a necessary tool if you want to know what effect position/equipment changes have in the real world, to back up wind tunnel testing.

I'm entirely unconvinced that anybody needs one for more than one day every 6 weeks.

That's ridiculous. If you're so convinced it's useful for measuring a training block why would you not measure everything? It makes no sense to ignore weeks of riding.