"Back of the Envelope" valuation?

I'm keen to hear from anyone about how they value assets.

Specifically valuing them quickly.

For instance, if you've ever invested in the stock market you might take a quick look at P/E ratios.

Or buying a house you might have a quick look at what other similar properties are priced at in the local area.

How much of a mindset shift was it for you to realise that this approach couldn't be replicated as quickly and easily for Bitcoin?