Congress does not have the constitutional authority to declare a prior Congresses laws invalid. For a bunch of internal stuff like the fillubuster rules, or remote voting, the current Congress can do whatever it wants without presidential review. However once a law is passed through the constitutional process, the constitution does not have a separate process for repealing it. This means that Congress would need to go through the same constitutional process to repeal it, which includes the possibility of a presidential veto.
Having said that, the Supreme Court does have the constitutional authority to declare a law invalid[0], and the President has no veto authority over that. Further, the current Supreme Court has invented out of nothingness two bedrock pillars of constitutional analysis:
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The Major Questions Doctrine, which states that questions of major political or economic significance may not be delegated by Congress to the executive branch.
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The Non-Delegation Doctrine, which states that Congress may not delegate it’s lawmaking authority to other entities.
Since the Supreme Court is an unbiased arbiter of the law, I’m confident that they will apply these principles consistently and determine that Congress’s initial delegation if tarrif authority was unconditional. /s
[0] This is not actually explicit in the Constitution. But has been how it is interpreted since Marbury v Madison in 1803.
I’ve used it a fair amount for memory mapped IO where the hardware defined bitfields. It is also useful when you have a data format with bitfields. I’d say it is also useful when your data does not respect byte boundaries, but the only time I’ve run into that involved the bit order being “backwards”, which means that I still had to bittwidle things back together.
From a performance perspective, a cache line is only 64 bytes. Space in registers, low level memory caches, and memory throughout are all limited as well.