First of all the sunk cost fallacy isn't so much a fallacy to begin with but just a bias. Which makes that more about psychology and economics than about philosophy.
Also whether the decision is wrong can usually only be confirmed after the fact, so it's rather about strategies and heuristics than about hard and fast rules where fallacies would apply.
Like whether it makes sense to continue investing or abandoning a project depends on the project. Like if you're only doing it to make money then you just calculate expected returns and expected loses and look whether the result is positive or negative. Either of which could be inflated or deflated by biases so yeah that's all just heuristics and a rule of thumb. But if the result of the project is crucial, idk a water purifier in a fallout scenario then it's almost irrelevant what the costs are as long as it solves the problem.
And in that situation. Well it depends on the quality of the big fix and hot fix. Like if the big fix is standardized, tested, calculated and whatnot and supposed to yield a 20% benefit, while the hot fix yields a 10% benefit but breaks some or all of the standardization that lets the big fix achieve it's 20% benefit. Then you'd not do the hot fix but rather wait for the big fix. If the systems are modular and independent and it really doesn't matter who does what, then the situation would be different. But either way it's not a fallacy it's a heuristic. And whether it makes sense depends on the situation that you're dealing with.
Also keep in mind that optimization is not neutral, there are multiple parameters by which you can optimize a system and there are usually multiple outputs that you may want or not want to optimize. So you might want to optimize your workload while management might want to optimize for money. And these two can at times be mutually exclusive.