Spring this year is like ages ago in terms of LLM development. I suspect that you would need to do considerably less checking now or none (it checks itself) with an up-to-date agent, if you use your harness correctly.

Let me put your point into perspective:

"Try calculating without a calculator and you'll quickly realize how dependent on it you've really become. I haven't used it at all since spring this year and it's been great. I actually get more work done without it since I don't have to double check the calculations anymore."

I think overdependence on LLMs is a valid concern, not restricted to coding. Studies would indicate as much. It's good to be able to write code yourself. But I wonder if that is really a skill that is going to continue to be necessary in the future. Being able to do big calculations in your head or on paper is a nice skill to have, even now, but it's honestly not absolutely necessary in today's world. It's good cognitive training, so I would still recommend it and basic arithmetic skills are necessary to understand higher maths and be able to use a calculator.

As I've pointed out in another comment, LLM companies are terrible for a variety of reasons and I despise their business models, but saying that the models are not useful is a notion not rooted in reality, imho.