That's one of my favourite aphorisms. "Back in the old days" it was easier to remember to double- and triple-check advertising or collateral before releasing it because everything was a hard copy. Now that so much of what we produce is digital it's easy to just dive in and release something as quickly as possible, telling yourself you'll fix any issues as they arise.
That's fine for something where being first to market is important - like an app, maybe - but most of the time it's preferable to take a bit of time to review and test. That could be anything from checking for typos to duplicating a website to test plugin updates rather than updating on the live site and hoping nothing breaks. It's a bit more upfront work but that bit of work is worth it to ensure your business always looks polished and professional.