Yeah, this is the real question.
It's a balance to know how much to make, and when to stop. I expect Mjolnir 3 will continue as a "Tier 3" product, which means "we get another run going when the current one is sold." Which translates to "there will be periods of 2 or so months where it's out of stock." There's nothing really keeping us from making more, other than waiting for the custom transformers/chokes/chassis/etc.
Folkvangr is a different case. That one was done as an intentionally limited run to use up a bunch of tubes. Which it did. If we did another run, it might cut into tube supply too much given that we're planning a Valhalla 3. Which may not be that big of a deal, because tubes are still kinda on the outs with many people, so all tube stuff is, ah, less pressing than it once was.
If I seem thoughtful/introspective, it's because I'm working on the end of the year chapter. Preview: it was a good year. Mostly. But it took a lot of work.