The answer is as usual: It depends...

It depends mostly on the case. It's obviously not important for market sizing cases or finance-heavy cases. But for anything to do with market entry, growth strategy, some cost improvement... of course it's important.

So the best thing to do is to always acknowledge that distribution is a thing, and go through the analysis where appropriate.

If you analyze distribution, here are a couple of thing:

• Which are the distribution channels a company is using? Why those, and why not others?
• What is the bargaining power of distributors (per channel)?
• What is the cost of distribution (per channel)?
• If appropriate for the case (i.e. a strategy case): Could distribution be organized completely different (e.g.: Tesla owns dealerships, other car manufacturers don't. "Direct to consumer" vs. through a multi-brand store...)

Hope this helps