Forgetting costs energy... Human memory seems association-based, and even uses the creative part of the brain so it can also generate details (often false) on the fly. So learning things via mnemonics is so successful even if counterintuitive that you're learning two things instead of one, but eventually the mnemonic seems to fade and you can deal with the thing you were after. But the mnemonic often seems to still be there. How do you deal with sudden recall of a memory or fact from 10+ years ago which you haven't thought about at all since then and that for all intents and purposes is useless and noise? There's a lot of stuff that is still 'there' in the brain, even if you can't recall, but may be triggered by some association, so how do you distinguish failure to recall with actual forgetting and the information not being there at all? The article mentions childhood phone numbers. I can remember at least one right now, it wouldn't surprise me if I could recall others with more careful thinking or perhaps some nostalgic browsing of old photos.
Changing locations is barely given a blurb in the article and I don't see how it would help that much apart from maybe motivation-related reasons (similar to having a separate room in your home for your home office). Is there a study on location changing? I'd bet the location trick's effects are dominated by the fact that spaced repetition is at play, which also gets mentioned in the article. Is there a study that tries to detect a difference between spaced repetition in the same location and spaced repetition in other locations? If there were a difference, then maybe it could work on the idea that you're creating a subconscious association with the place you're studying in and the thing you're learning, and by recalling and learning it in another location you're adding another association and strengthening the common paths. But I have to wonder if explicitly constructing a memory palace to create such associations between facts and things/places is a far superior strategy and again would dominate any effect of different location.