I also, once switching to gc2b, wore binders instead of sports bras all the time. I've survived 12 hour days (DONT DO THAT THOUGH) and I grew accustomed to longer times wearing it. I get sore and achey but that's more of a product of binding for years than anything and it would have happened eventually.
If you really can't wear it every day, I find sports bras worked for me in casual button downs but not formal ones. I HAVE to bind in a formal button down myself. Can you wear a vest, sweater, or blazer? An extra layer helps smooth things out and in an office setting it hopefully wouldn't be excruciatingly hot haha.
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