True, but if you knew the card well enough to remember it after that long then it's not unreasonable to think you might know it well enough again after another long wait. And as I've said before, we do put your highest-priority words first in an SRS test, and you can stop anytime you want and continue along later - we're just not going to put a "review only X cards at a time" option in because at that point you're really not doing SRS anymore.
I'd very much like to do something other than SRS, actually - I've never been a great believer in it (c.f. the many arguments we all had about this back in the Palm days), especially for long-term language learning. It does demand more disciplined scheduling than most people can find in their lives, it ignores real-world exposure to language, it necessitates the use of static 'facts' without any room for subtler associations between words (clozes are a lovely idea but they ought to be controlled by something very different from an SRS algorithm), and it's part of this larger fallacy of the key to learning Chinese being cramming your head full of vocabulary.
It's also part of the same awful phenomenon of education in general focusing more and more on 'metrics' - people feel good because they can pull up a report saying they've learned X many words or X many characters (perhaps helped along in the latter by a made-up useless who-cares-if-you-actually-understand-anything learning system like Chineasy), but that has about as much to do with your level of Chinese fluency as the number of lines of code you can write in an hour has to do with your level of computer programing skill. (if you're thinking this might be part of the reason why the Statistics screen has been allowed to languish in information-poor text-only obscurity for a decade or so, you're probably on to something)
Personally, my top advice to anyone learning Chinese with Pleco would be to take half of the time they're currently putting towards flashcards and put it into reading stuff with the document reader instead - there's a reason why so much of Pleco is oriented around doing things with words you haven't memorized.
At the same time, though, if we start from the assumption that SRS does work + that reviewing words at increasing intervals is the best way to commit them to long-term memory, simply putting your reviews on ice for 3 weeks is a terrible idea and would erase many of the gains you'd gotten from your recent vocabulary study. So it seems kind of disingenuous to put forward an SRS system and then let people undermine it in settings to the point where they're not actually doing SRS and are perhaps even worse off than they would be simply pulling cards from the deck randomly and reviewing those.
The basic problem is that so many people are dead set on this idea that SRS is the best way to learn vocabulary that to drop it or downplay it in Pleco would be borderline suicidal, so whatever alternative we came up with would have to be able to live happily alongside an SRS system so that people who want SRS can still get it. And that still constrains us somewhat in how much we can move away from our current flashcard paradigm towards something more humane and language-centric.
So inasmuch as there's a more user-friendly solution to this, it would probably be by explicitly sacrificing your progress with some words, as I've mentioned earlier - you say that you can't study for the next 3 weeks and then we basically triage, stop introducing new words, put short-interval words back into the pool of new words (but bring them back again first once you've caught up on your old reviews and are ready to start new words again), stretch out words with long intervals to even longer ones on the assumption that even a very good SRS algorithm is unlikely to be so accurate that it would know that a word needs to be reviewed after 110 days rather than 120, and if that's still not enough, use some combination of settings + algorithms to decide which words in your current pool are the ones you can most afford to forget when you don't review them often enough.
