The best thing you can do with a calc pack is throw it out.
I’ve encountered two schools of thought when checking designs.
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Get as much info from the designer as you can (calcs, spreadsheets, models, the lot); check they are correct.
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Refuse anything from the designer except the drawings and maybe the report. Then perform your own calculations to review the details.
I’m firmly in School #2.
I don’t care if you made an arithmetic error in your calcs, provided I agree with the detail you’ve put on the page.
And following a calc gets you in the mindset of assuming the methodology is correct, when it may not be. Just because a calculation flows, and the math all adds up doesn’t mean it’s the right approach for the design.
Some of the most important things on a drawing have no calculation behind them. Detailing, constructability, tolerances, setout. So you need to look at the bigger picture.
School #2 is definitely harder. You don’t have the designer’s time budget, so you can’t reproduce their work. You’re relying on rules of thumb, back-of-envelope checks, and a feel for whether a number is in the right postcode. It requires judgement which can be wrong and you can’t hide behind a spreadsheet when it is.
But hey, that’s the job.
When something is genuinely complex and needs detailed calculations or modelling, the checker should absolutely do this. Independently. Don’t check someone else’s model. Make sure there’s budget to build your own. If there’s no budget, say something. If your calcs and their calcs disagree, you’ve called the raise and it’s time to show cards.
Meanwhile the designer should live in both schools. Verify your own arithmetic and calc logic, sure. But also step back (perhaps even before starting…) and do a back-of-the-envelope check: what sort of answer am I expecting?
So next time someone hands you a calc pack, hit delete. Start with the drawings.
It’s harder. It’s also the only way you’ll ever enjoy checking someone’s design.